Continuous analyte sensor quality measures and related therapy actions for an automated therapy delivery system

ABSTRACT

Disclosed is a method of controlling operation of a medical device that regulates delivery of a fluid medication to a user. The method obtains a current sensor-generated value that is indicative of a physiological characteristic of the user, and is produced in response to operation of a continuous analyte sensor device. The method continues by: calculating a sensor quality metric that indicates reliability and trustworthiness of the current sensor-generated value; adjusting, in response to the calculated sensor quality metric, therapy actions of the medical device to configure a quality-specific operating mode of the medical device; managing generation of user alerts at the medical device in response to the calculated sensor quality metric; and regulating delivery of the fluid medication from the medical device, in accordance with the current sensor-generated value and the quality-specific operating mode of the medical device.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally to asystem that delivers therapy (e.g., medicine) to a user. Morespecifically, the subject matter described herein relates to userinterface and quality checking features of an insulin infusion systemthat obtains glucose readings from a continuous glucose sensor.

BACKGROUND

Medical therapy delivery systems, such as fluid infusion pump devices,are relatively well known in the medical arts, for use in delivering ordispensing an agent, such as insulin or another prescribed medication,to a patient. A typical infusion pump includes a pump drive system thatusually includes a small motor and drive train components that convertrotational motor motion to a translational displacement of a plunger (orstopper) in a fluid reservoir, which delivers medication from thereservoir to the body of a patient via a fluid path created between thereservoir and the body of a patient. Use of infusion pump therapy hasbeen increasing, especially for delivering insulin for diabetics.

Control schemes have been developed to allow insulin infusion pumps tomonitor and regulate a patient's blood glucose level in a substantiallycontinuous and autonomous manner. Managing a diabetic's blood glucoselevel is complicated by variations in a patient's daily activities(e.g., exercise, carbohydrate consumption, and the like) in addition tovariations in the patient's individual insulin response and potentiallyother factors. Some control schemes may attempt to proactively accountfor daily activities to minimize glucose excursions. At the same time,patients may manually initiate delivery of insulin prior to orcontemporaneously with consuming a meal (e.g., a meal bolus orcorrection bolus) to prevent spikes or swings in the patient's bloodglucose level that could otherwise result from the impending consumptionof carbohydrates and the response time of the control scheme.

BRIEF SUMMARY

Disclosed herein is a method of controlling operation of a medicaldevice that regulates delivery of a fluid medication to a user. Anembodiment of the method involves: receiving meter-generated values thatare indicative of a physiological characteristic of the user, themeter-generated values produced in response to operation of an analytemeter device; and obtaining sensor-generated values that are indicativeof the physiological characteristic of the user, the sensor-generatedvalues produced in response to operation of a continuous analyte sensordevice, different than the analyte meter device. When a validmeter-generated value is available, the medical device is operated in afirst mode to display the valid meter-generated value on a usermonitoring screen of the medical device and on a therapy deliverycontrol screen of the medical device, and operating the medical devicein the first mode to calculate therapy dosage for delivery based on thevalid meter-generated value. When a valid meter-generated value isunavailable and a current sensor-generated value of the sensor-generatedvalues satisfies first quality criteria, the medical device is operatedin a second mode to display the current sensor-generated value on theuser monitoring screen and on the therapy delivery control screen, andto calculate therapy dosage for delivery based on the currentsensor-generated value. When a valid meter-generated value isunavailable and the current sensor-generated value satisfies secondquality criteria but does not satisfy the first quality criteria, themedical device is operated in a third mode to display the currentsensor-generated value on the user monitoring screen, to inhibit displayof the current sensor-generated value on the therapy delivery controlscreen, and to inhibit use of the current sensor-generated value forpurposes of calculating therapy dosage for delivery.

Also disclosed herein is a medical device that regulates delivery ofmedication to a user. An embodiment of the medical device includes: adrive system; at least one processor device that regulates operation ofthe drive system to deliver a fluid medication from the medical device;a display device; and at least one memory element associated with the atleast one processor device, the at least one memory element storingprocessor-executable instructions configurable to be executed by the atleast one processor device to perform a method of controlling operationof the medical device. An embodiment of the method involves: receivingmeter-generated values that are indicative of a physiologicalcharacteristic of the user, the meter-generated values produced inresponse to operation of an analyte meter device; and obtainingsensor-generated values that are indicative of the physiologicalcharacteristic of the user, the sensor-generated values produced inresponse to operation of a continuous analyte sensor device, differentthan the analyte meter device. When a meter-generated value isavailable, the medical device is operated in a first mode to display, onthe display device, the valid meter-generated value on a user monitoringscreen and on a therapy delivery control screen, and to calculatetherapy dosage for delivery based on the valid meter-generated value.When a meter-generated value is unavailable and a currentsensor-generated value of the sensor-generated values satisfies firstquality criteria, the medical device is operated in a second mode todisplay, on the display device, the current sensor-generated value onthe user monitoring screen and on the therapy delivery control screen,and to calculate therapy dosage for delivery based on the currentsensor-generated value. When a valid meter-generated value isunavailable and the current sensor-generated value satisfies secondquality criteria but does not satisfy the first quality criteria, themedical device is operated in a third mode to display, on the displaydevice, the current sensor-generated value on the user monitoringscreen, to inhibit display of the current sensor-generated value on thetherapy delivery control screen, and to inhibit use of the currentsensor-generated value for purposes of calculating therapy dosage fordelivery.

Also disclosed herein is a non-transitory computer-readable storagemedium comprising program instructions stored thereon, wherein theprogram instructions are configurable to cause at least one processordevice to perform a method that involves: receiving meter-generatedvalues that are indicative of a physiological characteristic of theuser, the meter-generated values produced in response to operation of ananalyte meter device; and obtaining sensor-generated values that areindicative of the physiological characteristic of the user, thesensor-generated values produced in response to operation of acontinuous analyte sensor device, different than the analyte meterdevice. When a valid meter-generated value is available, the methodoperates the medical device in a first mode to display the validmeter-generated value on a user monitoring screen of the medical deviceand on a therapy delivery control screen of the medical device, andoperates the medical device in the first mode to calculate therapydosage for delivery based on the valid meter-generated value. When avalid meter-generated value is unavailable and a currentsensor-generated value satisfies first quality criteria, the methodoperates the medical device in a second mode to display the currentsensor-generated value on the user monitoring screen and on the therapydelivery control screen, and operates the medical device in the secondmode to calculate therapy dosage for delivery based on the currentsensor-generated value and not a meter-generated value. When a validmeter-generated value is unavailable and the current sensor-generatedvalue satisfies second quality criteria but does not satisfy the firstquality criteria, the method operates the medical device in a third modeto display the current sensor-generated value on the user monitoringscreen, operates the medical device in the third mode to inhibit displayof the current sensor-generated value on the therapy delivery controlscreen, and operates the medical device to inhibit use of the currentsensor-generated value for purposes of calculating therapy dosage fordelivery.

Also disclosed herein is a method of controlling operation of a medicaldevice that regulates delivery of a fluid medication to a user, themethod involving: obtaining a current sensor-generated value that isindicative of a physiological characteristic of the user, the currentsensor-generated value produced in response to operation of a continuousanalyte sensor device; calculating a sensor quality metric thatindicates reliability and trustworthiness of the currentsensor-generated value; adjusting, in response to the calculated sensorquality metric, therapy actions of the medical device to configure aquality-specific operating mode of the medical device; managinggeneration of user alerts at the medical device in response to thecalculated sensor quality metric; and regulating delivery of the fluidmedication from the medical device, in accordance with the currentsensor-generated value and the quality-specific operating mode of themedical device.

Also disclosed herein is a medical device that regulates delivery ofmedication to a user. The medical device includes: a drive system; atleast one processor device that regulates operation of the drive systemto deliver a fluid medication from the medical device; a user interface;and at least one memory element associated with the at least oneprocessor device, the at least one memory element storingprocessor-executable instructions configurable to be executed by the atleast one processor device to perform a method of controlling operationof the medical device. An embodiment of the method involves: obtaining acurrent sensor-generated value that is indicative of a physiologicalcharacteristic of the user, the current sensor-generated value producedin response to operation of a continuous analyte sensor device;receiving or calculating a sensor quality metric that indicatesreliability and trustworthiness of the current sensor-generated value;adjusting therapy actions of the medical device in response to thecalculated sensor quality metric, to configure a quality-specificoperating mode of the medical device; managing generation of user alertsat the user interface in response to the calculated sensor qualitymetric; and regulating delivery of the fluid medication from the medicaldevice, in accordance with the current sensor-generated value and thequality-specific operating mode of the medical device.

Also disclosed herein is a method of assessing operational quality of acontinuous analyte sensor device. An embodiment of the method involves:obtaining a current sensor-generated value that is indicative of aphysiological characteristic of the user, the current sensor-generatedvalue produced in response to operation of the continuous analyte sensordevice; calculating a sensor quality metric that indicates reliabilityand trustworthiness of the current sensor-generated value, wherein thecalculating is based on information generated by or derived from thecontinuous analyte sensor device; and formatting the sensor qualitymetric for compatibility with a fluid medication delivery device, suchthat therapy actions of the fluid medication delivery device areadjusted in response to the calculated sensor quality metric, and suchthat aggressiveness of fluid medication therapy provided by the fluidmedication delivery device is proportional to quality of the currentsensor-generated value as indicated by the calculated sensor qualitymetric.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 depicts an exemplary embodiment of an infusion system;

FIG. 2 depicts a plan view of an exemplary embodiment of a fluidinfusion device suitable for use in the infusion system of FIG. 1 ;

FIG. 3 is an exploded perspective view of the fluid infusion device ofFIG. 2 ;

FIG. 4 is a cross-sectional view of the fluid infusion device of FIGS.2-3 as viewed along line 4-4 in FIG. 3 when assembled with a reservoirinserted in the infusion device;

FIG. 5 is a block diagram of an exemplary infusion system suitable foruse with a fluid infusion device in one or more embodiments;

FIG. 6 is a block diagram of an exemplary pump control system suitablefor use in the infusion device in the infusion system of FIG. 5 in oneor more embodiments;

FIG. 7 is a block diagram of a closed-loop control system that may beimplemented or otherwise supported by the pump control system in thefluid infusion device of FIGS. 5-6 in one or more exemplary embodiments;

FIG. 8 is a block diagram of an exemplary patient monitoring system;

FIG. 9 is a flow chart that illustrates an exemplary embodiment of aprocess for operating a medical device, such as an insulin infusiondevice;

FIG. 10 is a flow chart that illustrates operation of an insulininfusion device in a first mode;

FIG. 11 is a schematic representation of a user monitoring screen on aninsulin infusion device, with a meter-generated blood glucose (BG) valuedisplayed thereon;

FIG. 12 is a schematic representation of a therapy delivery controlscreen on an insulin infusion device, with a BG value displayed thereon;

FIG. 13 is a flow chart that illustrates operation of an insulininfusion device in a second mode;

FIG. 14 is a schematic representation of a user monitoring screen on aninsulin infusion device, with a sensor-generated glucose (SG) valuedisplayed thereon;

FIG. 15 is a schematic representation of a therapy delivery controlscreen on an insulin infusion device, with an SG value displayedthereon;

FIG. 16 is a flow chart that illustrates operation of an insulininfusion device in a third mode;

FIG. 17 is a schematic representation of a therapy delivery controlscreen on an insulin infusion device, with neither a BG value nor an SGvalue displayed thereon;

FIG. 18 is a flow chart that illustrates an exemplary embodiment of amethod of controlling operation of a medical device to regulate therapyactions based on sensor quality;

FIG. 19 is a block diagram that illustrates the generation of a sensorquality metric in accordance with an exemplary embodiment; and

FIG. 20 is a flow chart that illustrates operation of an insulininfusion device in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

Exemplary embodiments of the subject matter described herein areimplemented in conjunction with medical devices, such as portableelectronic medical devices. Although many different applications arepossible, the following description focuses on embodiments thatincorporate an insulin infusion device (or insulin pump) as part of aninfusion system deployment. For the sake of brevity, conventionaltechniques related to infusion system operation, insulin pump and/orinfusion set operation, and other functional aspects of the systems (andthe individual operating components of the systems) may not be describedin detail here. Examples of infusion pumps may be of the type describedin, but not limited to, U.S. Pat. Nos. 4,562,751; 4,685,903; 5,080,653;5,505,709; 5,097,122; 6,485,465; 6,554,798; 6,558,320; 6,558,351;6,641,533; 6,659,980; 6,752,787; 6,817,990; 6,932,584; and 7,621,893;each of which are herein incorporated by reference.

Generally, a fluid infusion device includes a motor or other actuationarrangement that is operable to linearly displace a plunger (or stopper)of a fluid reservoir provided within the fluid infusion device todeliver a dosage of fluid medication, such as insulin, to the body of auser. Dosage commands that govern operation of the motor may begenerated in an automated manner in accordance with the delivery controlscheme associated with a particular operating mode, and the dosagecommands may be generated in a manner that is influenced by a current(or most recent) measurement of a physiological condition in the body ofthe user. For example, in a closed-loop or automatic operating mode,dosage commands may be generated based on a difference between a current(or most recent) measurement of the interstitial fluid glucose level inthe body of the user and a target (or reference) glucose setpoint value.In this regard, the rate of infusion may vary as the difference betweena current measurement value and the target measurement value fluctuates.For purposes of explanation, the subject matter is described herein inthe context of the infused fluid being insulin for regulating a glucoselevel of a user (or patient); however, it should be appreciated thatmany other fluids may be administered through infusion, and the subjectmatter described herein is not necessarily limited to use with insulin.

An insulin infusion pump can be operated in an automatic mode whereinbasal insulin is delivered at a rate that is automatically adjusted forthe user. While controlling the delivery of basal insulin in thismanner, the pump can also control the delivery of correction boluses toaccount for rising glucose trends due to meals, stress, hormonalfluctuations, etc. Ideally, the amount of a correction bolus should beaccurately calculated and administered to maintain the user's bloodglucose within the desired range. In particular, an automaticallygenerated and delivered correction bolus should safely manage the user'sblood glucose level and keep it above a defined hypoglycemic thresholdlevel.

Turning now to FIG. 1 , one exemplary embodiment of an infusion system100 includes, without limitation, a fluid infusion device (or infusionpump) 102, a sensing arrangement 104, a command control device (CCD)106, and a computer 108. The components of an infusion system 100 may berealized using different platforms, designs, and configurations, and theembodiment shown in FIG. 1 is not exhaustive or limiting. In someembodiments, the infusion device 102 and the sensing arrangement 104 aresecured at desired locations on the body of a user (or patient), asillustrated in FIG. 1 . In this regard, the locations at which theinfusion device 102 and the sensing arrangement 104 are secured to thebody of the user in FIG. 1 are provided only as a representative,non-limiting, example. The elements of the infusion system 100 may besimilar to those described in U.S. Pat. No. 8,674,288, the subjectmatter of which is hereby incorporated by reference in its entirety.

In the illustrated embodiment of FIG. 1 , the infusion device 102 isdesigned as a portable medical device suitable for infusing a fluid, aliquid, a gel, or other medicament into the body of a user. In exemplaryembodiments, the infused fluid is insulin, although many other fluidsmay be administered through infusion such as, but not limited to, HIVdrugs, drugs to treat pulmonary hypertension, iron chelation drugs, painmedications, anti-cancer treatments, medications, vitamins, hormones, orthe like. In some embodiments, the fluid may include a nutritionalsupplement, a dye, a tracing medium, a saline medium, a hydrationmedium, or the like.

The sensing arrangement 104 generally represents the components of theinfusion system 100 configured to sense, detect, measure or otherwisequantify a condition of the user, and may include a sensor, a monitor,or the like, for providing data indicative of the condition that issensed, detected, measured or otherwise monitored by the sensingarrangement. In this regard, the sensing arrangement 104 may includeelectronics and enzymes reactive to a biological condition, such as ablood glucose level, or the like, of the user, and provide dataindicative of the blood glucose level to the infusion device 102, theCCD 106 and/or the computer 108. For example, the infusion device 102,the CCD 106 and/or the computer 108 may include a display for presentinginformation or data to the user based on the sensor data received fromthe sensing arrangement 104, such as, for example, a current glucoselevel of the user, a graph or chart of the user's glucose level versustime, device status indicators, alert messages, or the like. In otherembodiments, the infusion device 102, the CCD 106 and/or the computer108 may include electronics and software that are configured to analyzesensor data and operate the infusion device 102 to deliver fluid to thebody of the user based on the sensor data and/or preprogrammed deliveryroutines. Thus, in exemplary embodiments, one or more of the infusiondevice 102, the sensing arrangement 104, the CCD 106, and/or thecomputer 108 includes a transmitter, a receiver, and/or othertransceiver electronics that allow for communication with othercomponents of the infusion system 100, so that the sensing arrangement104 may transmit sensor data or monitor data to one or more of theinfusion device 102, the CCD 106 and/or the computer 108.

Still referring to FIG. 1 , in various embodiments, the sensingarrangement 104 may be secured to the body of the user or embedded inthe body of the user at a location that is remote from the location atwhich the infusion device 102 is secured to the body of the user. Invarious other embodiments, the sensing arrangement 104 may beincorporated within the infusion device 102. In other embodiments, thesensing arrangement 104 may be separate and apart from the infusiondevice 102, and may be, for example, part of the CCD 106. In suchembodiments, the sensing arrangement 104 may be configured to receive abiological sample, analyte, or the like, to measure a condition of theuser.

In some embodiments, the CCD 106 and/or the computer 108 may includeelectronics and other components configured to perform processing,delivery routine storage, and to control the infusion device 102 in amanner that is influenced by sensor data measured by and/or receivedfrom the sensing arrangement 104. By including control functions in theCCD 106 and/or the computer 108, the infusion device 102 may be madewith more simplified electronics. However, in other embodiments, theinfusion device 102 may include all control functions, and may operatewithout the CCD 106 and/or the computer 108. In various embodiments, theCCD 106 may be a portable electronic device. In addition, in variousembodiments, the infusion device 102 and/or the sensing arrangement 104may be configured to transmit data to the CCD 106 and/or the computer108 for display or processing of the data by the CCD 106 and/or thecomputer 108.

In some embodiments, the CCD 106 and/or the computer 108 may provideinformation to the user that facilitates the user's subsequent use ofthe infusion device 102. For example, the CCD 106 may provideinformation to the user to allow the user to determine the rate or doseof medication to be administered into the user's body. In otherembodiments, the CCD 106 may provide information to the infusion device102 to autonomously control the rate or dose of medication administeredinto the body of the user. In some embodiments, the sensing arrangement104 may be integrated into the CCD 106. Such embodiments may allow theuser to monitor a condition by providing, for example, a sample of hisor her blood to the sensing arrangement 104 to assess his or hercondition. In some embodiments, the sensing arrangement 104 and the CCD106 may be used for determining glucose levels in the blood and/or bodyfluids of the user without the use of, or necessity of, a wire or cableconnection between the infusion device 102 and the sensing arrangement104 and/or the CCD 106.

In some embodiments, the sensing arrangement 104 and/or the infusiondevice 102 are cooperatively configured to utilize a closed-loop systemfor delivering fluid to the user. Examples of sensing devices and/orinfusion pumps utilizing closed-loop systems may be found at, but arenot limited to, the following U.S. Pat. Nos. 6,088,608, 6,119,028,6,589,229, 6,740,072, 6,827,702, 7,323,142, and 7,402,153 or UnitedStates Patent Application Publication No. 2014/0066889, all of which areincorporated herein by reference in their entirety. In such embodiments,the sensing arrangement 104 is configured to sense or measure acondition of the user, such as, blood glucose level or the like. Theinfusion device 102 is configured to deliver fluid in response to thecondition sensed by the sensing arrangement 104. In turn, the sensingarrangement 104 continues to sense or otherwise quantify a currentcondition of the user, thereby allowing the infusion device 102 todeliver fluid continuously in response to the condition currently (ormost recently) sensed by the sensing arrangement 104 indefinitely. Insome embodiments, the sensing arrangement 104 and/or the infusion device102 may be configured to utilize the closed-loop system only for aportion of the day, for example only when the user is asleep or awake.

FIGS. 2-4 depict one exemplary embodiment of a fluid infusion device 200(or alternatively, infusion pump) suitable for use in an infusionsystem, such as, for example, as infusion device 102 in the infusionsystem 100 of FIG. 1 . The fluid infusion device 200 is a portablemedical device designed to be carried or worn by a patient (or user),and the fluid infusion device 200 may leverage any number ofconventional features, components, elements, and characteristics ofexisting fluid infusion devices, such as, for example, some of thefeatures, components, elements, and/or characteristics described in U.S.Pat. Nos. 6,485,465 and 7,621,893. It should be appreciated that FIGS.2-4 depict some aspects of the infusion device 200 in a simplifiedmanner; in some embodiments, the infusion device 200 could includeadditional elements, features, or components that are not shown ordescribed in detail herein.

As best illustrated in FIGS. 2-3 , the illustrated embodiment of thefluid infusion device 200 includes a housing 202 adapted to receive afluid-containing reservoir 205. An opening 220 in the housing 202accommodates a fitting 223 (or cap) for the reservoir 205, with thefitting 223 being configured to mate or otherwise interface with tubing221 of an infusion set 225 that provides a fluid path to/from the bodyof the user. In this manner, fluid communication from the interior ofthe reservoir 205 to the user is established via the tubing 221. Theillustrated fluid infusion device 200 includes a human-machine interface(HMI) 230 (or user interface) that includes elements 232, 234 that canbe manipulated by the user to administer a bolus of fluid (e.g.,insulin), to change therapy settings, to change user preferences, toselect display features, and the like. The infusion device also includesa display device 226, such as a liquid crystal display (LCD) or anothersuitable display device, that can be used to present various types ofinformation or data to the user, such as, without limitation: thecurrent glucose level of the patient; the time; a graph or chart of thepatient's glucose level versus time; device status indicators; etc.

The housing 202 is formed from a substantially rigid material having ahollow interior 214 adapted to allow an electronics assembly 204, asliding member (or slide) 206, a drive system 208, a sensor assembly210, and a drive system capping member 212 to be disposed therein inaddition to the reservoir 205, with the contents of the housing 202being enclosed by a housing capping member 216. The opening 220, theslide 206, and the drive system 208 are coaxially aligned in an axialdirection (indicated by arrow 218), whereby the drive system 208facilitates linear displacement of the slide 206 in the axial direction218 to dispense fluid from the reservoir 205 (after the reservoir 205has been inserted into opening 220), with the sensor assembly 210 beingconfigured to measure axial forces (e.g., forces aligned with the axialdirection 218) exerted on the sensor assembly 210 responsive tooperating the drive system 208 to displace the slide 206. In variousembodiments, the sensor assembly 210 may be utilized to detect one ormore of the following: an occlusion in a fluid path that slows,prevents, or otherwise degrades fluid delivery from the reservoir 205 toa user's body; when the reservoir 205 is empty; when the slide 206 isproperly seated with the reservoir 205; when a fluid dose has beendelivered; when the infusion device 200 is subjected to shock orvibration; when the infusion device 200 requires maintenance.

Depending on the embodiment, the fluid-containing reservoir 205 may berealized as a syringe, a vial, a cartridge, a bag, or the like. Incertain embodiments, the infused fluid is insulin, although many otherfluids may be administered through infusion such as, but not limited to,HIV drugs, drugs to treat pulmonary hypertension, iron chelation drugs,pain medications, anti-cancer treatments, medications, vitamins,hormones, or the like. As best illustrated in FIGS. 3-4 , the reservoir205 typically includes a reservoir barrel 219 that contains the fluidand is concentrically and/or coaxially aligned with the slide 206 (e.g.,in the axial direction 218) when the reservoir 205 is inserted into theinfusion device 200. The end of the reservoir 205 proximate the opening220 may include or otherwise mate with the fitting 223, which securesthe reservoir 205 in the housing 202 and prevents displacement of thereservoir 205 in the axial direction 218 with respect to the housing 202after the reservoir 205 is inserted into the housing 202. As describedabove, the fitting 223 extends from (or through) the opening 220 of thehousing 202 and mates with tubing 221 to establish fluid communicationfrom the interior of the reservoir 205 (e.g., reservoir barrel 219) tothe user via the tubing 221 and infusion set 225. The opposing end ofthe reservoir 205 proximate the slide 206 includes a plunger 217 (orstopper) positioned to push fluid from inside the barrel 219 of thereservoir 205 along a fluid path through tubing 221 to a user. The slide206 is configured to mechanically couple or otherwise engage with theplunger 217, thereby becoming seated with the plunger 217 and/orreservoir 205. Fluid is forced from the reservoir 205 via tubing 221 asthe drive system 208 is operated to displace the slide 206 in the axialdirection 218 toward the opening 220 in the housing 202.

In the illustrated embodiment of FIGS. 3-4 , the drive system 208includes a motor assembly 207 and a drive screw 209. The motor assembly207 includes a motor that is coupled to drive train components of thedrive system 208 that are configured to convert rotational motor motionto a translational displacement of the slide 206 in the axial direction218, and thereby engaging and displacing the plunger 217 of thereservoir 205 in the axial direction 218. In some embodiments, the motorassembly 207 may also be powered to translate the slide 206 in theopposing direction (e.g., the direction opposite direction 218) toretract and/or detach from the reservoir 205 to allow the reservoir 205to be replaced. In exemplary embodiments, the motor assembly 207includes a brushless DC (BLDC) motor having one or more permanentmagnets mounted, affixed, or otherwise disposed on its rotor. However,the subject matter described herein is not necessarily limited to usewith BLDC motors, and in alternative embodiments, the motor may berealized as a solenoid motor, an AC motor, a stepper motor, apiezoelectric caterpillar drive, a shape memory actuator drive, anelectrochemical gas cell, a thermally driven gas cell, a bimetallicactuator, or the like. The drive train components may comprise one ormore lead screws, cams, ratchets, jacks, pulleys, pawls, clamps, gears,nuts, slides, bearings, levers, beams, stoppers, plungers, sliders,brackets, guides, bearings, supports, bellows, caps, diaphragms, bags,heaters, or the like. In this regard, although the illustratedembodiment of the infusion pump utilizes a coaxially aligned drivetrain, the motor could be arranged in an offset or otherwise non-coaxialmanner, relative to the longitudinal axis of the reservoir 205.

As best shown in FIG. 4 , the drive screw 209 mates with threads 402internal to the slide 206. When the motor assembly 207 is powered andoperated, the drive screw 209 rotates, and the slide 206 is forced totranslate in the axial direction 218. In an exemplary embodiment, theinfusion device 200 includes a sleeve 211 to prevent the slide 206 fromrotating when the drive screw 209 of the drive system 208 rotates. Thus,rotation of the drive screw 209 causes the slide 206 to extend orretract relative to the drive motor assembly 207. When the fluidinfusion device is assembled and operational, the slide 206 contacts theplunger 217 to engage the reservoir 205 and control delivery of fluidfrom the infusion device 200. In an exemplary embodiment, the shoulderportion 215 of the slide 206 contacts or otherwise engages the plunger217 to displace the plunger 217 in the axial direction 218. Inalternative embodiments, the slide 206 may include a threaded tip 213capable of being detachably engaged with internal threads 404 on theplunger 217 of the reservoir 205, as described in detail in U.S. Pat.Nos. 6,248,093 and 6,485,465, which are incorporated by referenceherein.

As illustrated in FIG. 3 , the electronics assembly 204 includes controlelectronics 224 coupled to the display device 226, with the housing 202including a transparent window portion 228 that is aligned with thedisplay device 226 to allow the display device 226 to be viewed by theuser when the electronics assembly 204 is disposed within the interior214 of the housing 202. The control electronics 224 generally representthe hardware, firmware, processing logic and/or software (orcombinations thereof) configured to control operation of the motorassembly 207 and/or drive system 208, as described in greater detailbelow in the context of FIG. 5 . The control electronics 224 is alsosuitably configured and designed to support various user interface,input/output, and display features of the fluid infusion device 200.Whether such functionality is implemented as hardware, firmware, a statemachine, or software depends upon the particular application and designconstraints imposed on the embodiment. Those familiar with the conceptsdescribed here may implement such functionality in a suitable manner foreach particular application, but such implementation decisions shouldnot be interpreted as being restrictive or limiting. In an exemplaryembodiment, the control electronics 224 includes one or moreprogrammable controllers that may be programmed to control operation ofthe infusion device 200.

The motor assembly 207 includes one or more electrical leads 236 adaptedto be electrically coupled to the electronics assembly 204 to establishcommunication between the control electronics 224 and the motor assembly207. In response to command signals from the control electronics 224that operate a motor driver (e.g., a power converter) to regulate theamount of power supplied to the motor from a power supply, the motoractuates the drive train components of the drive system 208 to displacethe slide 206 in the axial direction 218 to force fluid from thereservoir 205 along a fluid path (including tubing 221 and an infusionset), thereby administering doses of the fluid contained in thereservoir 205 into the user's body. Preferably, the power supply isrealized one or more batteries contained within the housing 202.Alternatively, the power supply may be a solar panel, capacitor, AC orDC power supplied through a power cord, or the like. In someembodiments, the control electronics 224 may operate the motor of themotor assembly 207 and/or drive system 208 in a stepwise manner,typically on an intermittent basis; to administer discrete precise dosesof the fluid to the user according to programmed delivery profiles.

Referring to FIGS. 2-4 , as described above, the user interface 230includes HMI elements, such as buttons 232 and a directional pad 234,that are formed on a graphic keypad overlay 231 that overlies a keypadassembly 233, which includes features corresponding to the buttons 232,directional pad 234 or other user interface items indicated by thegraphic keypad overlay 231. When assembled, the keypad assembly 233 iscoupled to the control electronics 224, thereby allowing the HMIelements 232, 234 to be manipulated by the user to interact with thecontrol electronics 224 and control operation of the infusion device200, for example, to administer a bolus of insulin, to change therapysettings, to change user preferences, to select display features, to setor disable alarms and reminders, and the like. In this regard, thecontrol electronics 224 maintains and/or provides information to thedisplay device 226 regarding program parameters, delivery profiles, pumpoperation, alarms, warnings, statuses, or the like, which may beadjusted using the HMI elements 232, 234. In various embodiments, theHMI elements 232, 234 may be realized as physical objects (e.g.,buttons, knobs, joysticks, and the like) or virtual objects (e.g.,graphical user interface elements that use touch-sensing and/orproximity-sensing technologies). For example, in some embodiments, thedisplay device 226 may be realized as a touch screen or touch-sensitivedisplay, and in such embodiments, the features and/or functionality ofthe HMI elements 232, 234 may be integrated into the display device 226and the HMI 230 may not be present. In some embodiments, the electronicsassembly 204 may also include alert generating elements coupled to thecontrol electronics 224 and suitably configured to generate one or moretypes of feedback, such as, without limitation: audible feedback; visualfeedback; haptic (physical) feedback; or the like.

Referring to FIGS. 3-4 , in accordance with one or more embodiments, thesensor assembly 210 includes a back plate structure 250 and a loadingelement 260. The loading element 260 is disposed between the cappingmember 212 and a beam structure 270 that includes one or more beamshaving sensing elements disposed thereon that are influenced bycompressive force applied to the sensor assembly 210 that deflects theone or more beams, as described in greater detail in U.S. Pat. No.8,474,332, which is incorporated by reference herein. In exemplaryembodiments, the back plate structure 250 is affixed, adhered, mounted,or otherwise mechanically coupled to the bottom surface 238 of the drivesystem 208 such that the back plate structure 250 resides between thebottom surface 238 of the drive system 208 and the housing cappingmember 216. The drive system capping member 212 is contoured toaccommodate and conform to the bottom of the sensor assembly 210 and thedrive system 208. The drive system capping member 212 may be affixed tothe interior of the housing 202 to prevent displacement of the sensorassembly 210 in the direction opposite the direction of force providedby the drive system 208 (e.g., the direction opposite direction 218).Thus, the sensor assembly 210 is positioned between the motor assembly207 and secured by the capping member 212, which prevents displacementof the sensor assembly 210 in a downward direction opposite thedirection of the arrow that represents the axial direction 218, suchthat the sensor assembly 210 is subjected to a reactionary compressiveforce when the drive system 208 and/or motor assembly 207 is operated todisplace the slide 206 in the axial direction 218 in opposition to thefluid pressure in the reservoir 205. Under normal operating conditions,the compressive force applied to the sensor assembly 210 is correlatedwith the fluid pressure in the reservoir 205. As shown, electrical leads240 are adapted to electrically couple the sensing elements of thesensor assembly 210 to the electronics assembly 204 to establishcommunication to the control electronics 224, wherein the controlelectronics 224 are configured to measure, receive, or otherwise obtainelectrical signals from the sensing elements of the sensor assembly 210that are indicative of the force applied by the drive system 208 in theaxial direction 218.

FIG. 5 depicts an exemplary embodiment of an infusion system 500suitable for use with an infusion device 502, such as any one of theinfusion devices 102, 200 described above. The infusion system 500 iscapable of controlling or otherwise regulating a physiological conditionin the body 501 of a patient to a desired (or target) value or otherwisemaintain the condition within a range of acceptable values in anautomated or autonomous manner. In one or more exemplary embodiments,the condition being regulated is sensed, detected, measured or otherwisequantified by a sensing arrangement 504 (e.g., a blood glucose sensingarrangement 504) communicatively coupled to the infusion device 502.However, it should be noted that in alternative embodiments, thecondition being regulated by the infusion system 500 may be correlativeto the measured values obtained by the sensing arrangement 504. Thatsaid, for clarity and purposes of explanation, the subject matter may bedescribed herein in the context of the sensing arrangement 504 beingrealized as a glucose sensing arrangement that senses, detects, measuresor otherwise quantifies the patient's glucose level, which is beingregulated in the body 501 of the patient by the infusion system 500.

In exemplary embodiments, the sensing arrangement 504 includes one ormore interstitial glucose sensing elements that generate or otherwiseoutput electrical signals (alternatively referred to herein asmeasurement signals) having a signal characteristic that is correlativeto, influenced by, or otherwise indicative of the relative interstitialfluid glucose level in the body 501 of the patient. The outputelectrical signals are filtered or otherwise processed to obtain ameasurement value indicative of the patient's interstitial fluid glucoselevel. In exemplary embodiments, a blood glucose meter 530, such as afinger stick device, is utilized to directly sense, detect, measure orotherwise quantify the blood glucose in the body 501 of the patient. Inthis regard, the blood glucose meter 530 outputs or otherwise provides ameasured blood glucose value that may be utilized as a referencemeasurement for calibrating the sensing arrangement 504 and converting ameasurement value indicative of the patient's interstitial fluid glucoselevel into a corresponding calibrated blood glucose value. For purposesof explanation, the calibrated blood glucose value calculated based onthe electrical signals output by the sensing element(s) of the sensingarrangement 504 may alternatively be referred to herein as the sensorglucose value, the sensed glucose value, or variants thereof.

In exemplary embodiments, the infusion system 500 also includes one ormore additional sensing arrangements 506, 508 configured to sense,detect, measure or otherwise quantify a characteristic of the body 501of the patient that is indicative of a condition in the body 501 of thepatient. In this regard, in addition to the glucose sensing arrangement504, one or more auxiliary sensing arrangements 506 may be worn,carried, or otherwise associated with the body 501 of the patient tomeasure characteristics or conditions of the patient (or the patient'sactivity) that may influence the patient's glucose levels or insulinsensitivity. For example, a heart rate sensing arrangement 506 could beworn on or otherwise associated with the patient's body 501 to sense,detect, measure or otherwise quantify the patient's heart rate, which,in turn, may be indicative of exercise (and the intensity thereof) thatis likely to influence the patient's glucose levels or insulin responsein the body 501. In yet another embodiment, another invasive,interstitial, or subcutaneous sensing arrangement 506 may be insertedinto the body 501 of the patient to obtain measurements of anotherphysiological condition that may be indicative of exercise (and theintensity thereof), such as, for example, a lactate sensor, a ketonesensor, or the like. Depending on the embodiment, the auxiliary sensingarrangement(s) 506 could be realized as a standalone component worn bythe patient, or alternatively, the auxiliary sensing arrangement(s) 506may be integrated with the infusion device 502 or the glucose sensingarrangement 504.

The illustrated infusion system 500 also includes an accelerationsensing arrangement 508 (or accelerometer) that may be worn on orotherwise associated with the patient's body 501 to sense, detect,measure or otherwise quantify an acceleration of the patient's body 501,which, in turn, may be indicative of exercise or some other condition inthe body 501 that is likely to influence the patient's insulin response.While the acceleration sensing arrangement 508 is depicted as beingintegrated into the infusion device 502 in FIG. 5 , in alternativeembodiments, the acceleration sensing arrangement 508 may be integratedwith another sensing arrangement 504, 506 on the body 501 of thepatient, or the acceleration sensing arrangement 508 may be realized asa separate standalone component that is worn by the patient.

In the illustrated embodiment, the pump control system 520 generallyrepresents the electronics and other components of the infusion device502 that control operation of the fluid infusion device 502 according toa desired infusion delivery program in a manner that is influenced bythe sensed glucose value indicating the current glucose level in thebody 501 of the patient. For example, to support a closed-loop operatingmode, the pump control system 520 maintains, receives, or otherwiseobtains a target or commanded glucose value, and automatically generatesor otherwise determines dosage commands for operating an actuationarrangement, such as a motor 532, to displace the plunger 517 anddeliver insulin to the body 501 of the patient based on the differencebetween the sensed glucose value and the target glucose value. In otheroperating modes, the pump control system 520 may generate or otherwisedetermine dosage commands configured to maintain the sensed glucosevalue below an upper glucose limit, above a lower glucose limit, orotherwise within a desired range of glucose values. In some embodiments,the infusion device 502 may store or otherwise maintain the targetvalue, upper and/or lower glucose limit(s), insulin delivery limit(s),and/or other glucose threshold value(s) in a data storage elementaccessible to the pump control system 520. As described in greaterdetail, in one or more exemplary embodiments, the pump control system520 automatically adjusts or adapts one or more parameters or othercontrol information used to generate commands for operating the motor532 in a manner that accounts for a likely change in the patient'sglucose level or insulin response resulting from a meal, exercise, orother activity.

Still referring to FIG. 5 , the target glucose value and other thresholdglucose values utilized by the pump control system 520 may be receivedfrom an external component (e.g., CCD 106 and/or computing device 108)or be input by a patient via a user interface element 540 associatedwith the infusion device 502. In some embodiments, the one or more userinterface element(s) 540 associated with the infusion device 502typically include at least one input user interface element, such as,for example, a button, a keypad, a keyboard, a knob, a joystick, amouse, a touch panel, a touchscreen, a microphone or another audio inputdevice, and/or the like. Additionally, the one or more user interfaceelement(s) 540 include at least one output user interface element, suchas, for example, a display device (e.g., a light-emitting diode or thelike), a display device (e.g., a liquid crystal display or the like), aspeaker or another audio output device, a haptic feedback device, or thelike, for providing notifications or other information to the patient.It should be noted that although FIG. 5 depicts the user interfaceelement(s) 540 as being separate from the infusion device 502, in someembodiments, one or more of the user interface element(s) 540 may beintegrated with the infusion device 502. Furthermore, in someembodiments, one or more user interface element(s) 540 are integratedwith the sensing arrangement 504 in addition to and/or in alternative tothe user interface element(s) 540 integrated with the infusion device502. The user interface element(s) 540 may be manipulated by the patientto operate the infusion device 502 to deliver correction boluses, adjusttarget and/or threshold values, modify the delivery control scheme oroperating mode, and the like, as desired.

Still referring to FIG. 5 , in the illustrated embodiment, the infusiondevice 502 includes a motor control module 512 coupled to a motor 532(e.g., motor assembly 207) that is operable to displace a plunger 517(e.g., plunger 217) in a reservoir (e.g., reservoir 205) and provide adesired amount of fluid to the body 501 of a patient. In this regard,displacement of the plunger 517 results in the delivery of a fluid, suchas insulin, that is capable of influencing the patient's physiologicalcondition to the body 501 of the patient via a fluid delivery path(e.g., via tubing 221 of an infusion set 225). A motor driver module 514is coupled between an energy source 518 and the motor 532. The motorcontrol module 512 is coupled to the motor driver module 514, and themotor control module 512 generates or otherwise provides command signalsthat operate the motor driver module 514 to provide current (or power)from the energy source 518 to the motor 532 to displace the plunger 517in response to receiving, from a pump control system 520, a dosagecommand indicative of the desired amount of fluid to be delivered.

In exemplary embodiments, the energy source 518 is realized as a batteryhoused within the infusion device 502 (e.g., within housing 202) thatprovides direct current (DC) power. In this regard, the motor drivermodule 514 generally represents the combination of circuitry, hardwareand/or other electrical components configured to convert or otherwisetransfer DC power provided by the energy source 518 into alternatingelectrical signals applied to respective phases of the stator windingsof the motor 532 that result in current flowing through the statorwindings that generates a stator magnetic field and causes the rotor ofthe motor 532 to rotate. The motor control module 512 is configured toreceive or otherwise obtain a commanded dosage from the pump controlsystem 520, convert the commanded dosage to a commanded translationaldisplacement of the plunger 517, and command, signal, or otherwiseoperate the motor driver module 514 to cause the rotor of the motor 532to rotate by an amount that produces the commanded translationaldisplacement of the plunger 517. For example, the motor control module512 may determine an amount of rotation of the rotor required to producetranslational displacement of the plunger 517 that achieves thecommanded dosage received from the pump control system 520. Based on thecurrent rotational position (or orientation) of the rotor with respectto the stator that is indicated by the output of the rotor sensingarrangement 516, the motor control module 512 determines the appropriatesequence of alternating electrical signals to be applied to therespective phases of the stator windings that should rotate the rotor bythe determined amount of rotation from its current position (ororientation). In embodiments where the motor 532 is realized as a BLDCmotor, the alternating electrical signals commutate the respectivephases of the stator windings at the appropriate orientation of therotor magnetic poles with respect to the stator and in the appropriateorder to provide a rotating stator magnetic field that rotates the rotorin the desired direction. Thereafter, the motor control module 512operates the motor driver module 514 to apply the determined alternatingelectrical signals (e.g., the command signals) to the stator windings ofthe motor 532 to achieve the desired delivery of fluid to the patient.

When the motor control module 512 is operating the motor driver module514, current flows from the energy source 518 through the statorwindings of the motor 532 to produce a stator magnetic field thatinteracts with the rotor magnetic field. In some embodiments, after themotor control module 512 operates the motor driver module 514 and/ormotor 532 to achieve the commanded dosage, the motor control module 512ceases operating the motor driver module 514 and/or motor 532 until asubsequent dosage command is received. In this regard, the motor drivermodule 514 and the motor 532 enter an idle state during which the motordriver module 514 effectively disconnects or isolates the statorwindings of the motor 532 from the energy source 518. In other words,current does not flow from the energy source 518 through the statorwindings of the motor 532 when the motor 532 is idle, and thus, themotor 532 does not consume power from the energy source 518 in the idlestate, thereby improving efficiency.

Depending on the embodiment, the motor control module 512 may beimplemented or realized with a general purpose processor, amicroprocessor, a controller, a microcontroller, a state machine, acontent addressable memory, an application specific integrated circuit,a field programmable gate array, any suitable programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof, designed to perform the functions described herein.In exemplary embodiments, the motor control module 512 includes orotherwise accesses a data storage element or memory, including any sortof random access memory (RAM), read only memory (ROM), flash memory,registers, hard disks, removable disks, magnetic or optical massstorage, or any other short or long term storage media or othernon-transitory computer-readable medium, which is capable of storingprogramming instructions for execution by the motor control module 512.The computer-executable programming instructions, when read and executedby the motor control module 512, cause the motor control module 512 toperform or otherwise support the tasks, operations, functions, andprocesses described herein.

It should be appreciated that FIG. 5 is a simplified representation ofthe infusion device 502 for purposes of explanation and is not intendedto limit the subject matter described herein in any way. In this regard,depending on the embodiment, some features and/or functionality of thesensing arrangement 504 may implemented by or otherwise integrated intothe pump control system 520, or vice versa. Similarly, in someembodiments, the features and/or functionality of the motor controlmodule 512 may implemented by or otherwise integrated into the pumpcontrol system 520, or vice versa. Furthermore, the features and/orfunctionality of the pump control system 520 may be implemented bycontrol electronics 224 located in the fluid infusion device 502, whilein alternative embodiments, the pump control system 520 may beimplemented by a remote computing device that is physically distinctand/or separate from the infusion device 502, such as, for example, theCCD 106 or the computing device 108.

FIG. 6 depicts an exemplary embodiment of a pump control system 600suitable for use as the pump control system 520 in FIG. 5 in accordancewith one or more embodiments. The illustrated pump control system 600includes, without limitation, a pump control module 602, acommunications interface 604, and a data storage element (or memory)606. The pump control module 602 is coupled to the communicationsinterface 604 and the memory 606, and the pump control module 602 issuitably configured to support the operations, tasks, and/or processesdescribed herein. In various embodiments, the pump control module 602 isalso coupled to one or more user interface elements (e.g., userinterface 230, 540) for receiving user inputs (e.g., target glucosevalues or other glucose thresholds) and providing notifications, alerts,or other therapy information to the patient.

The communications interface 604 generally represents the hardware,circuitry, logic, firmware and/or other components of the pump controlsystem 600 that are coupled to the pump control module 602 andconfigured to support communications between the pump control system 600and the various sensing arrangements 504, 506, 508. In this regard, thecommunications interface 604 may include or otherwise be coupled to oneor more transceiver modules capable of supporting wirelesscommunications between the pump control system 520, 600 and the sensingarrangement 504, 506, 508. For example, the communications interface 604may be utilized to receive sensor measurement values or othermeasurement data from each sensing arrangement 504, 506, 508 in aninfusion system 500. In other embodiments, the communications interface604 may be configured to support wired communications to/from thesensing arrangement(s) 504, 506, 508. In various embodiments, thecommunications interface 604 may also support communications withanother electronic device (e.g., CCD 106 and/or computer 108) in aninfusion system (e.g., to upload sensor measurement values to a serveror other computing device, receive control information from a server orother computing device, and the like).

The pump control module 602 generally represents the hardware,circuitry, logic, firmware and/or other component of the pump controlsystem 600 that is coupled to the communications interface 604 andconfigured to determine dosage commands for operating the motor 532 todeliver fluid to the body 501 based on measurement data received fromthe sensing arrangements 504, 506, 508 and perform various additionaltasks, operations, functions and/or operations described herein. Forexample, in exemplary embodiments, pump control module 602 implements orotherwise executes a command generation application 610 that supportsone or more autonomous operating modes and calculates or otherwisedetermines dosage commands for operating the motor 532 of the infusiondevice 502 in an autonomous operating mode based at least in part on acurrent measurement value for a condition in the body 501 of thepatient. For example, in a closed-loop operating mode, the commandgeneration application 610 may determine a dosage command for operatingthe motor 532 to deliver insulin to the body 501 of the patient based atleast in part on the current glucose measurement value most recentlyreceived from the sensing arrangement 504 to regulate the patient'sblood glucose level to a target reference glucose value. Additionally,the command generation application 610 may generate dosage commands forboluses that are manually-initiated or otherwise instructed by a patientvia a user interface element.

In exemplary embodiments, the pump control module 602 also implements orotherwise executes a personalization application 608 that iscooperatively configured to interact with the command generationapplication 610 to support adjusting dosage commands or controlinformation dictating the manner in which dosage commands are generatedin a personalized, patient-specific manner. In this regard, in someembodiments, based on correlations between current or recent measurementdata and the current operational context relative to historical dataassociated with the patient, the personalization application 608 mayadjust or otherwise modify values for one or more parameters utilized bythe command generation application 610 when determining dosage commands,for example, by modifying a parameter value at a register or location inmemory 606 referenced by the command generation application 610. In yetother embodiments, the personalization application 608 may predict mealsor other events or activities that are likely to be engaged in by thepatient and output or otherwise provide an indication of the predictedpatient behavior for confirmation or modification by the patient, which,in turn, may then be utilized to adjust the manner in which dosagecommands are generated to regulate glucose in a manner that accounts forthe patient's behavior in a personalized manner.

Still referring to FIG. 6 , depending on the embodiment, the pumpcontrol module 602 may be implemented or realized with at least onegeneral purpose processor device, a microprocessor, a controller, amicrocontroller, a state machine, a content addressable memory, anapplication specific integrated circuit, a field programmable gatearray, any suitable programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof, designed to perform the functions described herein. In thisregard, the steps of a method or algorithm described in connection withthe embodiments disclosed herein may be embodied directly in hardware,in firmware, in a software module executed by the pump control module602, or in any practical combination thereof. In exemplary embodiments,the pump control module 602 includes or otherwise accesses the datastorage element or memory 606, which may be realized using any sort ofnon-transitory computer-readable medium capable of storing programminginstructions for execution by the pump control module 602. Thecomputer-executable programming instructions, when read and executed bythe pump control module 602, cause the pump control module 602 toimplement or otherwise generate the applications 608, 610 and performtasks, operations, functions, and processes described herein.

It should be understood that FIG. 6 is a simplified representation of apump control system 600 for purposes of explanation and is not intendedto limit the subject matter described herein in any way. For example, insome embodiments, the features and/or functionality of the motor controlmodule 512 may be implemented by or otherwise integrated into the pumpcontrol system 600 and/or the pump control module 602, for example, bythe command generation application 610 converting the dosage commandinto a corresponding motor command, in which case, the separate motorcontrol module 512 may be absent from an embodiment of the infusiondevice 502.

FIG. 7 depicts an exemplary closed-loop control system 700 that may beimplemented by a pump control system 520, 600 to provide a closed-loopoperating mode that autonomously regulates a condition in the body of apatient to a reference (or target) value. In this regard, the controlsystem 700 can be utilized to regulate the delivery of insulin to thepatient during an automatic basal insulin delivery operation. It shouldbe appreciated that FIG. 7 is a simplified representation of the controlsystem 700 for purposes of explanation and is not intended to limit thesubject matter described herein in any way.

In exemplary embodiments, the control system 700 receives or otherwiseobtains a target glucose value at input 702. In some embodiments, thetarget glucose value may be stored or otherwise maintained by theinfusion device 502 (e.g., in memory 606), however, in some alternativeembodiments, the target value may be received from an external component(e.g., CCD 106 and/or computer 108). In one or more embodiments, thetarget glucose value may be calculated or otherwise determined prior toentering the closed-loop operating mode based on one or morepatient-specific control parameters. For example, the target bloodglucose value may be calculated based at least in part on apatient-specific reference basal rate and a patient-specific dailyinsulin requirement, which are determined based on historical deliveryinformation over a preceding interval of time (e.g., the amount ofinsulin delivered over the preceding 24 hours). The control system 700also receives or otherwise obtains a current glucose measurement value(e.g., the most recently obtained sensor glucose value) from the sensingarrangement 504 at input 704. The illustrated control system 700implements or otherwise provides proportional-integral-derivative (PID)control to determine or otherwise generate delivery commands foroperating the motor 532 based at least in part on the difference betweenthe target glucose value and the current glucose measurement value. Inthis regard, the PID control attempts to minimize the difference betweenthe measured value and the target value, and thereby regulates themeasured value to the desired value. PID control parameters are appliedto the difference between the target glucose level at input 702 and themeasured glucose level at input 704 to generate or otherwise determine adosage (or delivery) command provided at output 730. Based on thatdelivery command, the motor control module 512 operates the motor 532 todeliver insulin to the body of the patient to influence the patient'sglucose level, and thereby reduce the difference between a subsequentlymeasured glucose level and the target glucose level.

The illustrated control system 700 includes or otherwise implements asummation block 706 configured to determine a difference between thetarget value obtained at input 702 and the measured value obtained fromthe sensing arrangement 504 at input 704, for example, by subtractingthe target value from the measured value. The output of the summationblock 706 represents the difference between the measured and targetvalues, which is then provided to each of a proportional term path, anintegral term path, and a derivative term path. The proportional termpath includes a gain block 720 that multiplies the difference by aproportional gain coefficient, KP, to obtain the proportional term. Theintegral term path includes an integration block 708 that integrates thedifference and a gain block 722 that multiplies the integrateddifference by an integral gain coefficient, KI, to obtain the integralterm. The derivative term path includes a derivative block 710 thatdetermines the derivative of the difference and a gain block 724 thatmultiplies the derivative of the difference by a derivative gaincoefficient, KD, to obtain the derivative term. The proportional term,the integral term, and the derivative term are then added or otherwisecombined to obtain a delivery command that is utilized to operate themotor at output 730. Various implementation details pertaining toclosed-loop PID control and determining gain coefficients are describedin greater detail in U.S. Pat. No. 7,402,153, which is incorporated byreference.

In one or more exemplary embodiments, the PID gain coefficients arepatient-specific and dynamically calculated or otherwise determinedprior to entering the closed-loop operating mode based on historicalinsulin delivery information (e.g., amounts and/or timings of previousdosages, historical correction bolus information, or the like),historical sensor measurement values, historical reference blood glucosemeasurement values, user-reported or user-input events (e.g., meals,exercise, and the like), and the like. In this regard, one or morepatient-specific control parameters (e.g., an insulin sensitivityfactor, a daily insulin requirement, an insulin limit, a reference basalrate, a reference fasting glucose, an active insulin action duration,pharmodynamical time constants, or the like) may be utilized tocompensate, correct, or otherwise adjust the PID gain coefficients toaccount for various operating conditions experienced and/or exhibited bythe infusion device 502. The PID gain coefficients may be maintained bythe memory 606 accessible to the pump control module 602. In thisregard, the memory 606 may include a plurality of registers associatedwith the control parameters for the PID control. For example, a firstparameter register may store the target glucose value and be accessed byor otherwise coupled to the summation block 706 at input 702, andsimilarly, a second parameter register accessed by the proportional gainblock 720 may store the proportional gain coefficient, a third parameterregister accessed by the integration gain block 722 may store theintegration gain coefficient, and a fourth parameter register accessedby the derivative gain block 724 may store the derivative gaincoefficient.

In one or more exemplary embodiments, one or more parameters of theclosed-loop control system 700 are automatically adjusted or adapted ina personalized manner to account for potential changes in the patient'sglucose level or insulin sensitivity resulting from meals, exercise, orother events or activities. For example, in one or more embodiments, thetarget glucose value may be decreased in advance of a predicted mealevent to achieve an increase in the insulin infusion rate to effectivelypre-bolus a meal, and thereby reduce the likelihood of postprandialhyperglycemia. Additionally or alternatively, the time constant or gaincoefficient associated with one or more paths of the closed-loop controlsystem 700 may be adjusted to tune the responsiveness to deviationsbetween the measured glucose value and the target glucose value. Forexample, based on the particular type of meal being consumed or theparticular time of day during which the meal is consumed, the timeconstant associated with the derivative block 710 or derivative termpath may be adjusted to make the closed-loop control more or lessaggressive in response to an increase in the patient's glucose levelbased on the patient's historical glycemic response to the particulartype of meal.

FIG. 8 depicts an exemplary embodiment of a patient monitoring system800. The patient monitoring system 800 includes a medical device 802that is communicatively coupled to a sensing element 804 that isinserted into the body of a patient or otherwise worn by the patient toobtain measurement data indicative of a physiological condition in thebody of the patient, such as a sensed glucose level. The medical device802 is communicatively coupled to a client device 806 via acommunications network 810, with the client device 806 beingcommunicatively coupled to a remote device 814 via anothercommunications network 812. In this regard, the client device 806 mayfunction as an intermediary for uploading or otherwise providingmeasurement data from the medical device 802 to the remote device 814.It should be appreciated that FIG. 8 depicts a simplified representationof a patient monitoring system 800 for purposes of explanation and isnot intended to limit the subject matter described herein in any way.

In exemplary embodiments, the client device 806 is realized as a mobilephone, a smartphone, a tablet computer, or other similar mobileelectronic device; however, in other embodiments, the client device 806may be realized as any sort of electronic device capable ofcommunicating with the medical device 802 via network 810, such as alaptop or notebook computer, a desktop computer, or the like. Inexemplary embodiments, the network 810 is realized as a Bluetoothnetwork, a ZigBee network, or another suitable personal area network.That said, in other embodiments, the network 810 could be realized as awireless ad hoc network, a wireless local area network (WLAN), or localarea network (LAN). The client device 806 includes or is coupled to adisplay device, such as a monitor, screen, or another conventionalelectronic display, capable of graphically presenting data and/orinformation pertaining to the physiological condition of the patient.The client device 806 also includes or is otherwise associated with auser input device, such as a keyboard, a mouse, a touchscreen, or thelike, capable of receiving input data and/or other information from theuser of the client device 806.

In exemplary embodiments, a user, such as the patient, the patient'sdoctor or another healthcare provider, or the like, manipulates theclient device 806 to execute a client application 808 that supportscommunicating with the medical device 802 via the network 810. In thisregard, the client application 808 supports establishing acommunications session with the medical device 802 on the network 810and receiving data and/or information from the medical device 802 viathe communications session. The medical device 802 may similarly executeor otherwise implement a corresponding application or process thatsupports establishing the communications session with the clientapplication 808. The client application 808 generally represents asoftware module or another feature that is generated or otherwiseimplemented by the client device 806 to support the processes describedherein. Accordingly, the client device 806 generally includes aprocessing system and a data storage element (or memory) capable ofstoring programming instructions for execution by the processing system,that, when read and executed, cause processing system to create,generate, or otherwise facilitate the client application 808 and performor otherwise support the processes, tasks, operations, and/or functionsdescribed herein. Depending on the embodiment, the processing system maybe implemented using any suitable processing system and/or device, suchas, for example, one or more processor devices, central processing units(CPUs), controllers, microprocessors, microcontrollers, processing coresand/or other hardware computing resources configured to support theoperation of the processing system described herein. Similarly, the datastorage element or memory may be realized as a random-access memory(RAM), read only memory (ROM), flash memory, magnetic or optical massstorage, or any other suitable non-transitory short or long-term datastorage or other computer-readable media, and/or any suitablecombination thereof.

In one or more embodiments, the client device 806 and the medical device802 establish an association (or pairing) with one another over thenetwork 810 to support subsequently establishing a point-to-point orpeer-to-peer communications session between the medical device 802 andthe client device 806 via the network 810. For example, in accordancewith one embodiment, the network 810 is realized as a Bluetooth network,wherein the medical device 802 and the client device 806 are paired withone another (e.g., by obtaining and storing network identificationinformation for one another) by performing a discovery procedure oranother suitable pairing procedure. The pairing information obtainedduring the discovery procedure allows either of the medical device 802or the client device 806 to initiate the establishment of a securecommunications session via the network 810.

In one or more exemplary embodiments, the client application 808 is alsoconfigured to store or otherwise maintain an address and/or otheridentification information for the remote device 814 on the secondnetwork 812. In this regard, the second network 812 may be physicallyand/or logically distinct from the network 810, such as, for example,the Internet, a cellular network, a wide area network (WAN), or thelike. The remote device 814 generally represents a server or othercomputing device configured to receive and analyze or otherwise monitormeasurement data, event log data, and potentially other informationobtained for the patient associated with the medical device 802. Inexemplary embodiments, the remote device 814 is coupled to a database816 configured to store or otherwise maintain data associated withindividual patients. In some embodiments, the remote device 814 mayreside at a location that is physically distinct and/or separate fromthe medical device 802 and the client device 806, such as, for example,at a facility that is owned and/or operated by or otherwise affiliatedwith a manufacturer of the medical device 802. For purposes ofexplanation, but without limitation, the remote device 814 mayalternatively be referred to herein as a server.

Still referring to FIG. 8 , the sensing element 804 generally representsthe component of the patient monitoring system 800 that is configured togenerate, produce, or otherwise output one or more electrical signalsindicative of a physiological condition that is sensed, measured, orotherwise quantified by the sensing element 804. In this regard, thephysiological condition of a patient influences a characteristic of theelectrical signal output by the sensing element 804, such that thecharacteristic of the output signal corresponds to or is otherwisecorrelative to the physiological condition that the sensing element 804is sensitive to. In exemplary embodiments, the sensing element 804 isrealized as an interstitial glucose sensing element inserted at alocation on the body of the patient that generates an output electricalsignal having a current (or voltage) associated therewith that iscorrelative to the interstitial fluid glucose level that is sensed orotherwise measured in the body of the patient by the sensing element804.

The medical device 802 generally represents the component of the patientmonitoring system 800 that is communicatively coupled to the output ofthe sensing element 804 to receive or otherwise obtain the measurementdata samples from the sensing element 804 (e.g., the measured glucoseand characteristic impedance values), store or otherwise maintain themeasurement data samples, and upload or otherwise transmit themeasurement data to the remote device 814 or server via the clientdevice 806. In one or more embodiments, the medical device 802 isrealized as an infusion device 102, 200, 502 configured to deliver afluid, such as insulin, to the body of the patient. That said, in otherembodiments, the medical device 802 could be a standalone sensing ormonitoring device separate and independent from an infusion device(e.g., sensing arrangement 104, 504). It should be noted that althoughFIG. 8 depicts the medical device 802 and the sensing element 804 asseparate components, in some embodiments, the medical device 802 and thesensing element 804 may be integrated or otherwise combined to provide aunitary device that can be worn by the patient.

In exemplary embodiments, the medical device 802 includes a controlmodule 822, a data storage element 824 (or memory), and a communicationsinterface 826. The control module 822 generally represents the hardware,circuitry, logic, firmware and/or other component(s) of the medicaldevice 802 that is coupled to the sensing element 804 to receive theelectrical signals output by the sensing element 804 and perform orotherwise support various additional tasks, operations, functions and/orprocesses described herein. Depending on the embodiment, the controlmodule 822 may be implemented or realized with a general purposeprocessor device, a microprocessor device, a controller, amicrocontroller, a state machine, a content addressable memory, anapplication specific integrated circuit, a field programmable gatearray, any suitable programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof, designed to perform the functions described herein. In someembodiments, the control module 822 includes an analog-to-digitalconverter (ADC) or another similar sampling arrangement that samples orotherwise converts an output electrical signal received from the sensingelement 804 into corresponding digital measurement data value. In otherembodiments, the sensing element 804 may incorporate an ADC and output adigital measurement value.

The communications interface 826 generally represents the hardware,circuitry, logic, firmware and/or other components of the medical device802 that are coupled to the control module 822 for outputting dataand/or information from/to the medical device 802 to/from the clientdevice 806. For example, the communications interface 826 may include orotherwise be coupled to one or more transceiver modules capable ofsupporting wireless communications between the medical device 802 andthe client device 806. In exemplary embodiments, the communicationsinterface 826 is realized as a Bluetooth transceiver or adapterconfigured to support Bluetooth Low Energy (BLE) communications.

In exemplary embodiments, the remote device 814 receives, from theclient device 806, measurement data values associated with a particularpatient (e.g., sensor glucose measurements, acceleration measurements,and the like) that were obtained using the sensing element 804, and theremote device 814 stores or otherwise maintains the historicalmeasurement data in the database 816 in association with the patient(e.g., using one or more unique patient identifiers). Additionally, theremote device 814 may also receive, from or via the client device 806,meal data or other event log data that may be input or otherwiseprovided by the patient (e.g., via client application 808) and store orotherwise maintain historical meal data and other historical event oractivity data associated with the patient in the database 816. In thisregard, the meal data include, for example, a time or timestampassociated with a particular meal event, a meal type or otherinformation indicative of the content or nutritional characteristics ofthe meal, and an indication of the size associated with the meal. Inexemplary embodiments, the remote device 814 also receives historicalfluid delivery data corresponding to basal or bolus dosages of fluiddelivered to the patient by an infusion device 102, 200, 502. Forexample, the client application 808 may communicate with an infusiondevice 102, 200, 502 to obtain insulin delivery dosage amounts andcorresponding timestamps from the infusion device 102, 200, 502, andthen upload the insulin delivery data to the remote device 814 forstorage in association with the particular patient. The remote device814 may also receive geolocation data and potentially other contextualdata associated with a device 802, 806 from the client device 806 and/orclient application 808, and store or otherwise maintain the historicaloperational context data in association with the particular patient. Inthis regard, one or more of the devices 802, 806 may include a globalpositioning system (GPS) receiver or similar modules, components orcircuitry capable of outputting or otherwise providing datacharacterizing the geographic location of the respective device 802, 806in real-time.

The historical patient data may be analyzed by one or more of the remotedevice 814, the client device 806, and/or the medical device 802 toalter or adjust operation of an infusion device 102, 200, 502 toinfluence fluid delivery in a personalized manner. For example, thepatient's historical meal data and corresponding measurement data orother contextual data may be analyzed to predict a future time when thenext meal is likely to be consumed by the patient, the likelihood of afuture meal event within a specific time period, the likely size oramount of carbohydrates associated with a future meal, the likely typeor nutritional content of the future meal, and/or the like. Moreover,the patient's historical measurement data for postprandial periodsfollowing historical meal events may be analyzed to model or otherwisecharacterize the patient's glycemic response to the predicted size andtype of meal for the current context (e.g., time of day, day of week,geolocation, etc.). One or more aspects of the infusion device 102, 200,502 that control or regulate insulin delivery may then be modified oradjusted to proactively account for the patient's likely meal activityand glycemic response.

In one or more exemplary embodiments, the remote device 814 utilizesmachine learning to determine which combination of historical sensorglucose measurement data, historical delivery data, historical auxiliarymeasurement data (e.g., historical acceleration measurement data,historical heart rate measurement data, and/or the like), historicalevent log data, historical geolocation data, and other historical orcontextual data are correlated to or predictive of the occurrence of aparticular event, activity, or metric for a particular patient, and thendetermines a corresponding equation, function, or model for calculatingthe value of the parameter of interest based on that set of inputvariables. Thus, the model is capable of characterizing or mapping aparticular combination of one or more of the current (or recent) sensorglucose measurement data, auxiliary measurement data, delivery data,geographic location, patient behavior or activities, and the like to avalue representative of the current probability or likelihood of aparticular event or activity or a current value for a parameter ofinterest. It should be noted that since each patient's physiologicalresponse may vary from the rest of the population, the subset of inputvariables that are predictive of or correlative for a particular patientmay vary from other patients. Additionally, the relative weightingsapplied to the respective variables of that predictive subset may alsovary from other patients who may have common predictive subsets, basedon differing correlations between a particular input variable and thehistorical data for that particular patient. It should be noted that anynumber of different machine learning techniques may be utilized by theremote device 814 to determine what input variables are predictive for acurrent patient of interest, such as, for example, artificial neuralnetworks, genetic programming, support vector machines, Bayesiannetworks, probabilistic machine learning models, or other Bayesiantechniques, fuzzy logic, heuristically derived combinations, or thelike.

A medical device of the type described herein can generate various userinterface display screens that support different functions and features.For example, an insulin infusion device can generate a home screen thatserves as a patient status or monitoring screen, a settings/preferencesscreen, a bolus delivery control screen, and the like. These and otherdisplay screens can present the user with different information, statusdata, notifications, patient data (e.g., glucose data), and/or otherinformation in any desired arrangement or format.

Non-adjunctive insulin administration requires a sensor glucose (SG)value to be presented for bolus dosage estimation. The SG value shouldonly be presented to the user when it is accurate, reliable, orotherwise trusted. A user may instead choose to use a blood glucose (BG)value from a linked blood glucose meter device (e.g., a blood glucosemeter device in wireless or wired communication with the medicaldevice). Given that there are two sources of inputs for therapy, andonly one source may be used, the insulin infusion device is suitablyconfigured to clearly indicate which glucose source is being used. Tothis end, the exemplary embodiment described here is controlled in anappropriate manner to avoid using a current SG value for bolusestimation when it is determined that the quality or reliability of theSG value is not sufficiently high. The exemplary embodiment also safelydisambiguates SG from BG, for purposes of bolus estimation andpresentation to the user.

The operating methodology described in more detail below is governed bycertain rules when handling BG and SG values. For example, when a BGvalue is provided to the system, that value is displayed on a bolusdelivery control screen until the BG value is expired (e.g., after adesignated period of time, such as 12 minutes). A unique and visuallydistinguishable icon is used to indicate that the displayed value is aBG value. If the user fails to make a bolus delivery selection within apredefined period of time (e.g., 12 minutes or any other period oftime), the bolus delivery feature will timeout.

In accordance with another operating rule, when an SG value is trustedby the system and there is no recent BG entry, the bolus deliverycontrol screen includes the current SG value with a corresponding iconin a manner that is visually distinguishable from a displayed BG value.The SG value displayed within the bolus delivery screen cannot bemodified via the user interface of the insulin infusion device.

In accordance with another operating rule, if there is a sudden spike inSG readings (e.g., the SG increases at a rate that is higher than apredetermined threshold value) that cannot be attributed to carbohydrateingestion or other physiological processes, the current SG value isassumed to be temporarily unsuitable for non-adjunctive therapy. In thatinstance, no alert is required, but the SG value is not presented on thebolus delivery control screen, and the SG value is not used to calculatea bolus estimate.

Accordingly, the insulin infusion device supports a user interfaceassociated with fully non-adjunctive bolus estimation. The current SGvalue is intuitively displayed in the bolus delivery control screen whenit is a stable/trusted value. Otherwise, the SG value is removed fromthe bolus delivery control screen without generating a user alert. Ifthe user desires to administer a manual bolus, then user can provide aBG value to be used for bolus estimation. The display screens and userinterface features are designed such that the SG value is clearlydisambiguated from the BG value. This avoids user confusion andpotential bolus estimation errors.

FIG. 9 is a flow chart that illustrates an exemplary embodiment of aprocess 900 for operating a medical device that regulates delivery of afluid medication to a user. The process 900 may be performed by aninsulin infusion device of the type described above or any other medicaldevice. The process 900 receives meter-generated values that areindicative of a physiological characteristic of the user, wherein thegenerated values are produced in response to operation of an analytemeter device. For the exemplary implementation described here, themedical device is an insulin infusion device, the fluid medication isinsulin, the physiological characteristic of interest is blood glucose,and the meter-generated values are BG values obtained from a bloodglucose meter device (e.g., a BG fingerstick device) that generates BGmeasurements from a blood sample taken from the user. Thus, theexemplary embodiment of the process 900 receives BG values (e.g., once aday, every 12 hours, or as often as desired by the user), eitherdirectly from a linked BG meter or via manual data entry by a user orcaregiver at the insulin infusion device (task 902). The insulininfusion device assumes that recently received BG measurements (whetherthey are user-entered or received directly from a BG meter device) areaccurate and trustworthy.

The process 900 also obtains sensor-generated values that are indicativeof the same physiological characteristic of the user, wherein thesensor-generated values are produced in response to operation of acontinuous analyte sensor device. For the exemplary insulin infusiondevice implementation described here, the sensor-generated values are SGvalues obtained from a continuous glucose monitor or sensor (orcalculated from sensor data obtained from a continuous glucose monitoror sensor) that is worn by the user. Thus, the exemplary embodiment ofthe process 900 obtains SG values periodically, e.g., every fiveminutes, every ten minutes, or any other desired period of time (task904). In some embodiments, tasks 902 and 904 are performed independentlyof one another. For example, task 904 may be performed more often thantask 902, or tasks 902 and 904 may be performed serially in any order orconcurrently.

The process 900 determines how to use the BG value and/or the SG valuefor display purposes and for therapy dosage and delivery purposes. Tothis end, the exemplary embodiment of the process 900 checks for thepresence of a valid BG value, e.g., a valid meter-generated value (querytask 906). For this particular implementation, a current BG value isdeemed to be “valid” until it expires after an expiration time period.The expiration time period may vary from one embodiment to another. Forthis particular example, BG values have a valid lifespan of only 12minutes; stale BG values are not used. Thus, if the process 900determines that a valid BG value is available (the “Yes” branch of querytask 906), then the device is controlled in an appropriate manner tooperate in a first mode, e.g., as described in further detail withrespect to FIG. 10 below (task 908). In accordance with the embodimentdescribed here, the device is operated in the first mode when a validmeter-generated BG value is available, regardless of the availability ofa sensor-generated SG value, and regardless of the quality, accuracy, ortrustworthiness of the current SG value (if one is available).

FIG. 10 is a flow chart that illustrates operation of the insulininfusion device in the first mode. The first mode operation process 1000depicted in FIG. 10 can be performed at task 908 of the process 900.

In this example, a “fresh” BG value is assumed to be accurate andtrustworthy. Accordingly, the process 1000 displays the valid BG valueon a user monitoring screen of the device (task 1002). This BG valueremains displayed on the user monitoring screen while it remains valid.Once the BG value expires or is otherwise deemed to be invalid, it isremoved from the user monitoring screen (e.g., ceased to be displayedwithin the user monitoring screen). In some embodiments, the usermonitoring screen is a home screen of the insulin infusion device, andthe home screen may include additional information if so desired, suchas other patient data, status indicators, etc. In this regard, FIG. 11is a schematic representation of a user monitoring screen 1100 on aninsulin infusion device, with a current and valid meter-generated BGvalue 1102 displayed thereon. The BG value 1102 can be displayed with a“BG” label 1104 to make it obvious that the displayed value is indeed aBG value (rather than an SG value). Moreover, the process 1000 displaysthe BG value using visually distinguishable characteristics, which mayalso be used for displaying the “BG” label 1104 and for displaying theunits of the BG value (mg/dL). For example, any one or more of thefollowing visually distinguishable characteristics can be utilized fordisplaying the BG value: color; font design; font size; fontcharacteristics such as bold, italic, or outlined; animation such as aflashing display or a moving display; fill pattern or stippling; levelof transparency; and an accompanying icon (such as a blood drop).

Referring back to FIG. 10 , the process 1000 also displays the valid BGvalue on a therapy delivery control screen of the device (task 1004).The BG value remains displayed on the therapy delivery control screenwhile it remains valid. Once the BG value expires or is otherwise deemedto be invalid, it is removed from the therapy delivery control screen.For this particular embodiment, the therapy delivery control screen isan insulin bolus delivery control screen of the insulin infusion device,and the bolus delivery control screen may include additional informationrelated to an estimated bolus dosage and the operation of the bolusdelivery function. In this regard, FIG. 12 is a schematic representationof a therapy delivery control screen 1200 on an insulin infusion device,with the current and valid BG value 1202 displayed thereon. The BG value1202 can be displayed with a “BG” label 1204 to make it obvious that thedisplayed value is indeed a BG value (rather than an SG value). Inaddition, the BG value 1202 can be displayed with a visuallydistinguishable and contextually relevant icon 1206 to further indicatethat the displayed value is a BG value rather than an SG value. For thisexample, the icon 1206 resembles a drop of blood, and the icon 1206 iscolored red.

Notably, the process 1000 displays the BG value 1202 using the same (orsubstantially similar) visually distinguishable characteristics used todisplay the BG value 1102 on the user monitoring screen 1100. The samevisually distinguishable characteristics may also be used for displayingthe “BG” label 1204 and for displaying the units of the BG value(mg/dL). Using the same visually distinguishable characteristics for theBG value across different user interface screens or features makes iteasy for the user to interpret and recognize the source of the displayedglucose measurement. Although this description focuses on the usermonitoring screen and the therapy delivery control screen, consistentvisual characteristics (“look and feel” aspects) can be used across anynumber of display screens generated by the device.

Referring back to FIG. 10 , the process 1000 inhibits the display of anySG value on the user monitoring screen and on the therapy deliverycontrol screen (task 1006). In this regard, if a valid BG value isavailable, then the device relies on that measurement, whether or not acurrent and accurate SG value is also available. Thus, preventingdisplay of an available SG value under these conditions is intuitive andless confusing for users.

The process 1000 continues by calculating therapy dosage (if needed) fordelivery, based on the valid meter-generated BG value (task 1008). Forthis example, an insulin bolus is calculated at task 1008, and thecalculated bolus amount is displayed on the therapy delivery controlscreen. In this regard, the therapy delivery control screen 1200 shownin FIG. 12 includes a calculated insulin bolus of 0.8 Units. Thus, thevalid BG value serves as an input or parameter for purposes ofestimating an appropriate insulin bolus to maintain the user's bloodglucose level within a desired target range.

In some embodiments, the calculated bolus amount can be automatically ormanually administered. For example, the bolus can be automaticallydelivered if automatic delivery mode is supported and active.Accordingly, during operation in the first mode, the process 1000enables an automatic therapy delivery function of the device (task1010). Consequently, if the user fails to manually administer thecalculated bolus amount, the automatic delivery function will takeappropriate action to deliver the bolus in a timely manner. To this end,the process 1000 may automatically control the operation of the deviceto regulate delivery of the fluid medication (insulin) from the device,in accordance with the calculated therapy dosage (task 1012).

Returning to FIG. 9 and the description of the process 900, if a validBG value is unavailable (the “No” branch of query task 906), then theprocess 900 checks the current SG value to determine a measure ofquality. The quality of the current SG value can be determined orcalculated using any appropriate methodology. For example, the currentSG value can be compared against historical SG measurements, historicalBG measurements, the most recent BG value, or the like. Additionally oralternatively, the quality of the current SG value can be determinedusing a “self-diagnostic” technique that considers the age of thecontinuous glucose sensor, SG measurement trends, electrical noise inthe raw sensor signals, etc. In accordance with certain embodiments, theprocess 900 determines the quality of the SG measurements using themethodology described in more detail below.

Although the quality of SG measurements can be expressed in any suitablemanner, the exemplary embodiment of the process 900 considers “highquality” SG measurements to be the best quality (e.g., above ahigh-quality threshold) and, therefore, appropriate for purposes ofglucose monitoring, for therapy dosage calculation, and for controllingthe delivery of therapy. The process 900 considers “monitor quality” SGmeasurements to be appropriate for glucose monitoring only, whereinmonitor quality SG measurements are less desirable than high quality SGmeasurements, yet still suitable for certain non-therapy relatedfunctions (e.g., below the high-quality threshold and above alow-quality threshold). If the quality of an SG measurement is deemed tobe less than monitor quality (e.g., below the low-quality threshold),then that SG value is neither displayed nor used for therapy relatedfunctions.

If the process 900 determines that the current SG value satisfies “highquality” criteria, e.g., quality above the high-quality threshold (the“Yes” branch of query task 910), then the device is controlled in anappropriate manner to operate in a second mode (task 912). In accordancewith the embodiment described here, the device is operated in the secondmode when a valid meter-generated BG value is unavailable, and when thecurrent sensor-generated SG value is determined to be of high quality.

FIG. 13 is a flow chart that illustrates operation of the insulininfusion device in the second mode. The second mode operation process1300 depicted in FIG. 13 can be performed at task 912 of the process900. The second mode relies on the high quality SG value, which iscurrently available for use. Accordingly, the process 1300 displays thecurrent SG value on the user monitoring screen of the device (task1302). This SG value remains displayed on the user monitoring screenuntil it is refreshed. FIG. 14 is a schematic representation of a usermonitoring screen 1400 on the insulin infusion device, with the currentSG value 1402 displayed thereon. The SG value 1402 can be displayed withan “SG” label (not shown) to make it obvious that the displayed value isindeed an SG value (rather than a BG value). The example shown in FIG.14 displays glucose trend arrows 1404 near the displayed SG value 1402to indicate whether the user's blood glucose level is increasing ordecreasing (e.g., compared to previous glucose level measurements).Moreover, the process 1300 displays the SG value 1402 using visuallydistinguishable characteristics, which may also be used for displayingthe “SG” label, the trend arrows 1404, and the units of the SG value(mg/dL). The embodiment described here uses color as the visuallydistinguishable characteristic. In some embodiments, however, any one ormore of the following characteristics can be utilized for displaying theSG value: color; font design; font size; font characteristics such asbold, italic, or outlined; animation such as a flashing display or amoving display; fill pattern or stippling; level of transparency; and anaccompanying icon. Notably, SG values and BG values are displayed usingdifferent visually distinguishable characteristics, such that the usercan quickly and easily observe whether the displayed measurement is a BGvalue or an SG value. For example, BG values and related information canbe rendered in a white or yellow font, while SG values and relatedinformation can be rendered in an obviously contrasting color, such asblue, cyan, or purple.

Referring back to FIG. 13 , the process 1300 also displays the currentSG value on the therapy delivery control screen of the device (task1304). The SG value remains displayed on the therapy delivery controlscreen until it gets refreshed, and it cannot be modified via the userinterface of the device. FIG. 15 is a schematic representation of atherapy delivery control screen 1500 on an insulin infusion device, withthe current (and high quality) SG value 1502 displayed thereon. The SGvalue 1502 can be displayed with an “SG” label 1504 to make it obviousthat the displayed value is indeed an SG value (rather than a BG value).In addition, the SG value 1502 can be displayed with a visuallydistinguishable and contextually relevant icon 1506 to further indicatethat the displayed value is an SG value rather than a BG value. For thisexample, the icon 1506 resembles a plot or signal waveform, and the icon1506 is colored to match the color of the displayed SG value 1502.

Notably, the process 1300 displays the SG value 1502 using the same (orsubstantially similar) visually distinguishable characteristics used todisplay the SG value 1402 on the user monitoring screen 1400. The samevisually distinguishable characteristics may also be used for displayingthe “SG” label 1504 and for displaying the units of the SG value(mg/dL). Using the same visually distinguishable characteristics for theSG value across different user interface screens or features makes iteasy for the user to interpret and recognize the source of the displayedglucose measurement. Although this description focuses on the usermonitoring screen and the therapy delivery control screen, consistentvisual characteristics (“look and feel” aspects) can be used across anynumber of display screens generated by the device.

Referring back to FIG. 13 , the process 1300 inhibits the display of anyBG value on the user monitoring screen and on the therapy deliverycontrol screen (task 1306). In this regard, if a valid BG value isunavailable, then the device only considers a current (e.g., the mostrecent) and accurate SG value for display purposes.

The process 1300 continues by calculating therapy dosage (if needed) fordelivery, based on the high-quality sensor-generated SG value (task1308). For this example, an insulin bolus is calculated at task 1308,and the calculated bolus amount is displayed on the therapy deliverycontrol screen. In this regard, the therapy delivery control screen 1500shown in FIG. 15 includes a calculated insulin bolus of 0.8 Units. Thus,the high quality SG value serves as an input or parameter for purposesof estimating an appropriate insulin bolus to maintain the user's bloodglucose level within a desired target range.

In some example, the calculated bolus amount can be manuallyadministered or automatically delivered if automatic delivery mode issupported and active. Accordingly, during operation in the second mode,the process 1300 enables the automatic therapy delivery function of thedevice (task 1310). Consequently, if the user fails to manuallyadminister the calculated bolus amount, the automatic delivery functionwill take appropriate action to deliver the bolus in a timely manner. Tothis end, the process 1300 may automatically control the operation ofthe device to regulate delivery of the fluid medication (insulin) fromthe device, in accordance with the calculated therapy dosage (task1312).

Returning to FIG. 9 and the description of the process 900, if thecurrent SG value does not satisfy the “high quality” criteria (the “No”branch of query task 910), but satisfies “monitor quality” criteria (the“Yes” branch of query task 914), then the device is controlled in anappropriate manner to operate in a third mode (task 916). In accordancewith the embodiment described here, the device is operated in the thirdmode when a valid meter-generated BG value is unavailable, and when thecurrent sensor-generated SG value is determined to be of sufficientquality for user monitoring purposes but potentially unsuitable forcalculating therapy dosage.

FIG. 16 is a flow chart that illustrates operation of the insulininfusion device in the third mode. The third mode operation process 1600depicted in FIG. 16 can be performed at task 916 of the process 900. Thethird mode relies on the monitor quality SG value, which is currentlyavailable for use. Accordingly, the process 1600 displays the current SGvalue on the user monitoring screen of the device (task 1602). This SGvalue remains displayed on the user monitoring screen until it isrefreshed. The above description of the user monitoring screen 1400 (seeFIG. 14 ) also applies to this scenario because the monitor quality SGvalue is displayed in a similar fashion, with the same visuallydistinguishable characteristics described previously in connection withthe exemplary display shown in FIG. 14 .

While operating in the third mode, the device inhibits the display ofthe current SG value on the therapy delivery control screen (task 1604).In addition, the process 1600 inhibits the display of any BG value onthe therapy delivery control screen (task 1606). Instead, the device isoperated to display an appropriate message, notification, or indicationon the therapy delivery control screen, wherein the displayed contentindicates that no suitable measurement of the physiologicalcharacteristic of the user is available. For this particular example,the process 1600 displays a message such as “No Glucose” or “No GlucoseAvailable” on the therapy delivery control screen (task 1608). FIG. 17is a schematic representation of a therapy delivery control screen 1700on an insulin infusion device, with neither a BG value nor an SG valuedisplayed thereon. Instead, the therapy delivery control screen 1700includes a “No Glucose” message or field 1702 that lets the user knowthat no suitable glucose measurement is available for purposes ofcalculating an estimated bolus. Consequently, the therapy deliverycontrol screen 1700 indicates a bolus amount of 0.0 Units under theseconditions.

Referring back to FIG. 16 , the process 1600 inhibits the use of thecurrent SG value for purposes of calculating therapy dosage for delivery(task 1610). Although a monitor quality SG value is suitable for use asa general indicator of the user's glucose level, the process 1600assumes that it is potentially unsuitable for use in calculating aprecise insulin bolus amount. Accordingly, the process 1600 operates thedevice in the third mode to disable the automatic therapy deliveryfunction (task 1612). For the embodiment described here, task 1612ensures that correction boluses of insulin are not administered whilethe insulin infusion device is operating in the third mode.

The process 1600 may continue by prompting the user to obtain a newmeter-generated BG value (task 1614), which can be used to update theuser monitoring screen and the therapy delivery control screen.Moreover, a fresh BG value can be used to calculate an estimated bolusand to reactivate the automatic therapy delivery feature. Additionallyor alternatively, the process 1600 may generate a reminder, message, ornotification to prompt the user to check the integrity of the sensordevice, to recalibrate the sensor device, to replace the sensor devicewith a new unit, or the like.

Referring again to FIG. 9 , if the process 900 determines that thecurrent SG value does not satisfy the designated “monitor quality”criteria (the “No” branch of query task 914), then the process 900generates an appropriate alert, message, or notification regarding theneed to take some form of corrective action (task 918). For example, thedevice may generate an alert to remind the user to take one or more ofthe following actions: obtain/enter a new BG value; check the integrityof the currently deployed sensor device; recalibrate the currentlydeployed sensor device; check the data communication functionality ofthe currently deployed sensor device; replace the sensor device with anew unit; or the like.

The process 900 is performed in an ongoing manner that contemplatesupdating of the BG value and/or the SG value over time. The dashed linesin FIG. 9 indicate how the process 900 is repeated as needed to receiveand process new BG and SG values.

Automated insulin infusion systems that use feedback from a continuousglucose monitor (CGM) to adjust insulin dosing need to implement safetyfeatures to mitigate risk of over-delivery and hypoglycemia undercertain glucose sensor conditions. These mitigations may employ one ormore of the following technology components: (1) detection and rating ofCGM measurement quality for use in automatic insulin dosing; (2) a setof therapy adjustments that are appropriate for each level of sensorquality; (3) a set of system alerts or other user interface (UI)notifications that guide the user to the appropriate action if needed.An example of an insulin infusion system that utilizes a sensor qualitymetric to adjust therapy delivery modes is described above.

Sensor Quality—A high quality CGM/sensor measurement is needed torealize the full advantages of an automated insulin infusion system togovern basal and bolus insulin deliveries. The sensor quality metric maybe determined using known factors that may affect sensor accuracy.Examples of these factors include, without limitation: (1) sensor agethat has known correlations to measurement accuracy; (2) measurementnoise in the CGM electronics and/or raw sensor signals; (3) a suddensharp rise or fall in sensor measurement that cannot be attributed to anatural physiological condition.

In accordance with an exemplary embodiment, the sensor quality metricmay be mapped onto a scale (e.g., a scale of 1-10, or Low/Medium/Highvalues) that provides different quality grades that can be used toadjust the therapy. The determination of the specific grade should beassociated with the potential risk of providing automated therapy giventhe expected level of sensor error as a result of the underlyingcondition. For example, transient measurement noise may result inmoderate CGM measurement error, so it may correspond to a “medium”sensor quality metric, whereas a sudden, discontinuous jump or drop in aCGM measurement may correspond to a “low” sensor quality metric forpurposes of this description.

The sensor quality metric may also depend on characteristics ofhistorical CGM values in a time series. For example, previous CGM valuesfor a moving window of time can be analyzed and compared against thecurrent value. As another example, an average of historical CGM valuesobtained at or near the same time of day can be analyzed and comparedagainst the current value (obtained at the time of day under analysis).Accordingly, if a sufficient amount of historical values are notavailable, this condition itself may result in a conservative sensorquality rating until enough historical values are be recorded.

Therapy Adjustments—Once a sensor quality metric is determined, anadjustment to the control algorithm or methodology that governsautomated insulin infusion may be necessary to mitigate risks of over orunder delivery of insulin. In some embodiments, the specific type ofadjustment is dependent on the design of the automated infusionalgorithm.

As an example, consider an automated infusion algorithm that uses CGMmeasurements to make real-time adjustments to basal insulin and provideadditional bolus insulin during times of rapidly rising glucose.Furthermore, this algorithm contains a safe fallback delivery mode thatprovides a constant basal rate for times when the CGM measurement is notavailable. In such a system, the following cases may be considered fortherapy adjustment:

Case 1: “High” CGM/sensor quality metric—The algorithm may use its fullauthority of basal and bolus insulin based on the CGM measurements.

Case 2: “Medium” CGM/sensor quality metric—Allow only basal insulindelivery to be determined using the CGM but cease or otherwise limit thedelivery of bolus insulin.

Case 3: “Low” CGM/sensor quality metric—Ignore the CGM altogether andrevert to the safe fallback delivery mode until the sensor qualityrecovers.

The three cases listed above are representative examples for ahypothetical automated insulin infusion system. A different algorithmdesign would require therapy adjustments that are matched to thealgorithm's dosing rules and/or other factors.

System Alerts and Notifications—System alerts and notificationsrepresent another component to help manage risk while balancing therapyeffectiveness and user burden. It is most desirable to maintainacceptable therapy without adding the burden of system alerts thatinterrupt the user. However, in some cases an alert is necessary tofurther mitigate risks related to poor CGM quality or to guide the userthe action needed to recover optimal therapy.

For example, a particular CGM quality condition may be known to betransient in nature and generally recover without any intervention. Inthis case it may be appropriate for the system to make the therapyadjustment without notifying the user. However, a condition may beincluded to notify the user if the CGM quality is not fully recoveredafter a specified period of time.

As another example, a different CGM quality condition may be known torequire a calibration using an external blood glucose measurement torecover. In this case it would be appropriate to alert the user that aCGM calibration is required once this condition occurs.

As mentioned above, the sensor quality metric can be scaled in anydesirable manner. In accordance with an exemplary embodiment, the sensorquality metric can be “unknown” or “uncertain” or it can indicate low,medium, or high sensor quality. Table 1 indicates all of the sensorquality metrics for such an implementation, along with their relatedtherapy actions, and system alerts.

TABLE 1 Sensor Quality and Corresponding Actions Sensor Quality MetricDefinition Cause Therapy Action User Alert Uncertain Sensor qualityInsufficient sensor data Deliver automatic None cannot be collected forquality basal insulin only; determined assessment No automatic bolus LowSensor quality is not Rapid change due to Revert to safe Request BGreliable for hardware issues fallback mode measurement governing therapyfor calibration Medium Sensor quality is New or old sensor; Deliverautomatic None appropriate for Transient measurement basal insulin;conservative therapy noise; Low sensor Reduced authority of sensitivityautomatic boluses High Sensor quality is N/A Full automated basal Nonegood for full therapy and bolus insulin therapy

FIG. 18 is a flow chart that illustrates an exemplary embodiment of aprocess 1800 for controlling operation of a medical device to regulatetherapy actions based on sensor quality. The process 1800 obtains acurrent sensor-generated value that is indicative of a physiologicalcharacteristic of the user, where the value is produced in response tooperation of a continuous analyte sensor device. The embodimentpresented here relates to an insulin infusion system that includes orcooperates with a continuous glucose sensor—the physiologicalcharacteristic is a glucose level.

The process 1800 obtains a current SG value from a CGM sensor device(task 1802). The process 1800 calculates, receives, or otherwise obtainsa sensor quality metric for the CGM sensor device, where the sensorquality metric indicates accuracy, reliability, and/or trustworthinessof the current sensor-generated SG value (task 1804). In accordance withcertain embodiments, the sensor quality metric is calculated by the CGMsensor device, which communicates the calculated sensor quality metricto one or more destination devices as needed (for example, thecalculated sensor quality metric can be sent from the CGM sensor deviceto the insulin infusion device, to a glucose monitor device, to a mobiledevice running a suitably configured mobile app, or the like).Alternatively, or additionally, the sensor quality metric can becalculated by one or more devices other than the CGM sensor device,based on raw sensor signals or information generated at the CGM sensordevice. For example, the CGM sensor device can provide its electricaloutput (such as electrical current values or voltages) to the insulininfusion device, which then calculates the sensor quality metric basedon the provided electrical output values.

The process 1800 continues by adjusting therapy actions of the insulininfusion device in response to the sensor quality metric, to configure aquality-specific operating mode of the insulin infusion device (task1806), as described in more detail below with reference to FIG. 20 .Thus, therapy-related functions, features, and/or operations of themedical device (the insulin infusion device) are altered based on thecalculated sensor quality metric, e.g., high-quality, medium-quality,low-quality, etc. As shown in Table 1, conservative or aggressiveinsulin therapy options can be enabled/disabled in an ongoing manner,depending on the current state of the sensor quality metric. Moreover,the process 1800 manages the generation of user alerts at the medicaldevice in response to the calculated sensor quality metric (task 1808).In this regard, the process 1800 controls the insulin infusion device(and/or other user devices) to generate, inhibit, or otherwise regulateuser alerts, based on the current state of the sensor quality metric. Insome embodiments, task 1808 manages alerts by generating user alertswhen the calculated sensor quality metric satisfies designatedalert-generating criteria, and inhibits user alerts when the calculatedsensor quality metric fails the designated alert-generating criteria.The alert-generating criteria can be designated to reduce unwanted orannoyance alerts, alarms, and notifications. For example, thealert-generating criteria may inhibit user alerts if the sensor qualitymetric is “better” than low. As another example, the alert-generatingcriteria may permit user alerts if the sensor quality metric is low, orif the system determines that the sensor is at its end of life or haslost communication with the medical device. This provides a better userexperience with less nuisance alerts and less worrisome notifications.

The process 1800 continues by regulating delivery of fluid medication(e.g., insulin) from the medical device, in accordance with the currentSG value and in accordance with the quality-specific operating mode ofthe medical device (task 1810). In other words, the delivery of thefluid medication is controlled in response to the current sensor qualitymetric, which determines the quality-specific operating mode to be used,which results in an adjustment of certain specified therapy actions (seeTable 1). For this particular implementation, task 1810 adjusts thetherapy actions of the insulin infusion device such that aggressivenessof the insulin delivery therapy is proportional to the quality of thecurrent SG value, as indicated by the calculated sensor quality metric,as described in more detail below with reference to FIG. 20 . Dependingon the particular application and the type of medical device, thetherapy actions can be adjusted, controlled, or regulated in a differentmanner using any desired methodology or algorithm that is driven byvalues of the sensor quality metric. The process 1800 can be repeated inan ongoing manner to contemplate updated SG values and theircorresponding sensor quality metrics for purposes of adjusting thetherapy actions over time.

FIG. 19 is a block diagram that illustrates the generation of a sensorquality metric in accordance with an exemplary embodiment. FIG. 19depicts sensor quality calculation logic 1900 that calculates the sensorquality metric 1902 from one or more data inputs. The sensor qualitycalculation logic 1900 may reside and be executed at: the CGM sensordevice; the insulin infusion device; a user monitoring device; a mobiledevice; a smart device or appliance; a cloud-based system, device, orservice; a computing system or device onboard a vehicle; a tablet,desktop, or portable computer; or the like. Although not alwaysrequired, the exemplary embodiment presented here calculates the sensorquality metric 1902 only from information, data, or signals generated byor derived from the continuous analyte sensor device. In other words,the data inputs of the sensor quality calculation logic 1900 aregenerated by the sensor device or are derived/calculated from datagenerated by the sensor device, and no information from externalcalibrating devices or information from ancillary devices is processedby the sensor quality calculation logic 1900 to obtain the sensorquality metric 1902. In this regard, the continuous analyte sensordevice can generate its own sensor quality metric 1902 in an “isolated”and self-diagnosing manner without relying on any additional informationobtained from another device or system. Alternatively, the continuousanalyte sensor device can provide its internally produced or calculatedinformation to a compatible destination device, which then computes thesensor quality metric 1902 using only the information obtained from thesensor device.

In some examples, the data input utilized by the sensor qualitycalculation logic 1900 may be chosen to suit the needs and requirementsof the particular medical device system, the intended application,and/or the specific embodiment. The example shown in FIG. 19 processesat least the following data inputs: sensor age data 1904; raw sensorsignal values 1906; and/or historical sensor-generated values 1908produced in response to operation of the continuous analyte sensordevice. As mentioned above, these three data inputs are generated by thesensor device or are derived from information/data generated by thesensor device.

The sensor age data 1904 indicates a chronological age, operating lifeor “runtime” of the sensor device, the amount of time since deploymentof the sensor device, or the like. In this regard, the sensor age data1904 can be based on the date/time of manufacture, the date/time ofinitial deployment on the body of the user, the date/time followinginitialization or warmup of the sensor device following deployment, etc.Preferred implementations base the age of the sensor device on a timeimmediately following initialization or warmup of the deployed sensordevice, which can be determined or marked by the sensor device incertain implementations. The sensor device can keep track of its age andupdate the sensor age data 1904 in an ongoing manner over time.Alternatively or additionally, the sensor device can mark and report theinitial date/time (following warmup), to enable a destination device tokeep track of the sensor age and update the sensor age data 1904 as timeprogresses.

The raw sensor signal values 1906 correspond to the raw signal output ofthe continuous analyte sensor device, which is produced while the sensordevice is monitoring the physiological characteristic of interest. Incertain embodiments, the raw sensor signal values 1906 are electricalcurrent and/or electrical voltage measurements. For the continuousglucose sensor example described here, the raw sensor signal values 1906are electrical current readings that are sometimes referred to as “ISIG”values. The raw sensor signal values 1906 are processed or convertedinto the monitored analyte levels, such as blood glucose values. To thisend, the sensor-generated values 1908 depicted in FIG. 19 represent theusable sensor values that are derived from, calculated from, orconverted from the raw sensor signal values 1906. The methodologydescribed here considers a number of historical sensor-generated values1908 as needed to generate the sensor quality metric 1902 that isassociated with the current sensor value.

In certain embodiments, the sensor quality calculation logic 1900calculates the sensor quality metric 1902 based on: the sensor age data1904; measurement noise of the raw signal output of the continuousanalyte sensor device; and changes in the sensor-generated values 1908that cannot be attributed to a natural physiological condition of theuser. The sensor age data 1904 is considered because accuracy of a newlydeployed sensor device usually fluctuates for a short period of timeimmediately following the initialization or warmup period. Measurementnoise in the raw sensor signal values 1906 can be caused by variousconditions, such as physical movement of the sensor device, dislodgingof the embedded sensor element, sudden unpredictable changes inphysiology, ingress of water or other substances at the sensor site, orthe like. The raw sensor signal values 1906 are usually relativelystable over “long” periods of time such as five minutes. If, however,the sensor quality calculation logic 1900 detects high variation(measurement noise) in the raw sensor signal values 1906, then thecorresponding sensor measurements can be designated as low quality.Similarly, if the sensor-generated values 1908 exhibit sharp changes,spikes, or unrealistic measurements that do not correspond to normalphysiological changes or conditions, then the sensor quality calculationlogic 1900 can flag those sensor values as low quality or disregardthem.

The sensor quality calculation logic 1900 may consider any of the inputdata items individually or in any combination to generate the sensorquality metric 1902. As mentioned previously, the sensor quality metric1902 can be expressed in any desired format, using any desired range,scale, or domain. For the exemplary embodiment presented here, thesensor quality metric 1902 is calculated to be a number between 0 and 10(inclusive), but only four of the available metric values are mapped tothe quality states indicated in Table 1: Uncertain; Low; Medium; andHigh. In other embodiments, more or less than four quality states may beutilized. The sensor quality metric 1902 is generated and formatted inan appropriate manner for compatibility with a fluid medication deliverydevice, such that therapy actions of the fluid medication deliverydevice are adjusted in response to the calculated sensor quality metric.

The sensor quality calculation logic 1900 performs a method of assessingoperational quality of the continuous analyte sensor device, with thesensor quality metric 1902 serving as an indication of the quality. Thesensor quality metric 1902 can be utilized to regulate, control, oradjust certain functions or features of an associated medical devicethat regulates the delivery of therapy to a patient. In this regard,FIG. 20 is a flow chart that illustrates operation of an insulininfusion device in accordance with an exemplary embodiment (process2000) for sensor quality calculation logic 1900. The followingdescription of the process 2000 assumes that the insulin infusion devicereceives or generates sensor quality metrics with corresponding SGvalues, as described above. Accordingly, the illustrated embodiment ofthe process 2000 begins by processing the current value of the sensorquality metric (task 2002). For this particular implementation, theprocess 2000 checks whether the sensor quality metric indicatesUncertain quality (query task 2004), High quality (query task 2012),Medium quality (query task 2020), or Low quality (query task 2028).

When the sensor quality metric indicates Uncertain quality (the “Yes”branch of query task 2004), the process 2000 adjusts certain therapyactions of the insulin infusion device to configure an operating modethat is appropriate for the Uncertain quality status. More specifically,when the sensor quality metric indicates Uncertain quality, the process2000 enables automatic basal insulin delivery by the insulin infusiondevice (task 2006), disables an automatic bolus delivery feature of theinsulin infusion device (task 2008), and inhibits generation of any useralert related to the current sensor-generated value having Uncertainquality (task 2010). The therapy adjustments made for this particularoperating mode are appropriate under the assumption that the sensorquality metric will be determined in the near future. Thus, no useralert is generated, but the automatic bolus delivery function istemporarily disabled.

When the sensor quality metric indicates High quality, e.g., the sensorquality metric is greater than or equal to a high threshold value, suchas 7 (the “Yes” branch of query task 2012), the process 2000 adjustscertain therapy actions of the insulin infusion device to configure anappropriate high quality operating mode. More specifically, when thesensor quality metric indicates High quality, the process 2000 enablesautomatic basal insulin delivery by the insulin infusion device (task2014), enables the automatic bolus delivery feature (task 2016), andinhibits generation of any user alert related to the currentsensor-generated value having high quality (task 2018). The therapyadjustments made for this high quality operating mode are appropriateunder the assumption that the sensor device is operating in a normal andaccurate manner. To this end, no user alert is generated, and bothautomatic basal delivery and automatic bolus delivery remain active andenabled.

When the sensor quality metric indicates Medium quality, e.g., thesensor quality metric is between a low threshold value (such as 3) and ahigh threshold value (such as 7) (the “Yes” branch of query task 2020),the process 2000 adjusts certain therapy actions of the insulin infusiondevice to configure an appropriate medium quality operating mode. Morespecifically, when the sensor quality metric indicates Medium quality,the process 2000 enables automatic basal insulin delivery by the insulininfusion device (task 2022), enables a restricted automatic bolusdelivery feature (task 2024), and inhibits generation of any user alertrelated to the current sensor-generated value having medium quality(task 2026). The therapy adjustments made for this medium qualityoperating mode are appropriate under the assumption that the sensordevice is operating in a manner that can still support a modifiedautomatic bolus delivery function. Accordingly, no user alert isgenerated and automatic basal delivery remains active. However, theautomatic bolus delivery function is modified to be less aggressive thanusual. For example, the amount of insulin delivered by the automaticbolus delivery function may be limited or capped by some amount, or thebolus amount that is calculated from the current SG value may be reducedby a certain percentage as a safety factor. As another example, when thesensor quality metric indicates Medium quality, the insulin infusiondevice may be controlled in a way that places an upper limit on thecurrent SG value for purposes of calculating and administering anautomatic bolus. In accordance with certain embodiments, when the sensorquality metric indicates Medium quality, a maximum SG value is utilizedfor purposes of bolus calculation (e.g., 250 mg/dL)—if the current SGvalue is higher than the maximum allowable SG value, then the actual SGvalue is disregarded for purposes of automatic bolus calculation. Thismethodology reduces the likelihood of delivering too much insulin whenthe reliability or quality of the continuous glucose sensor device ispotentially questionable.

When the sensor quality metric indicates Low quality, e.g., the sensorquality metric is less than or equal to a low threshold value, such as 3(the “Yes” branch of query task 2028), the process 2000 adjusts certaintherapy actions of the insulin infusion device to configure anappropriate low quality operating mode. More specifically, when thesensor quality metric indicates Low quality, the process 2000 enables asafe basal insulin delivery mode of the insulin infusion device (task2030), disables the automatic bolus delivery feature (task 2032), andgenerates a user alert to prompt the user to take corrective action,such as obtaining a new blood glucose meter value for sensor calibration(task 2034). The therapy adjustments made for this low quality operatingmode result in conservative insulin therapy. To this end, the normalbasal insulin delivery profile for the user may be adjusted to begenerally less aggressive, or the basal delivery profile may be adjustedto be a flat profile that merely provides a baseline amount of basalinsulin over time. Moreover, automatic bolus delivery is suspended untilthe sensor quality metric improves.

As outlined above, low aggressiveness in the fluid medication therapy isprovided when the sensor quality metric is low (e.g., at or below a lowthreshold value), medium aggressiveness is provided when the sensorquality metric is medium (e.g., between the low threshold value and ahigh threshold value), and high aggressiveness is provided when thesensor quality metric is high (e.g., at or above the high thresholdvalue). Depending on the implementation, more or less than three levelsof aggressiveness may be supported.

If the sensor quality metric indicates quality worse than Low quality,or indicates an erroneous value, then the process 2000 may generate anappropriate alert, message, or notification regarding the need toinvestigate, take corrective action, or the like (task 2036). Forexample, the insulin infusion device may generate an audible alert anddisplay a message that asks the user to check the integrity of thesensor device, recalibrate the sensor device, replace the sensor device,etc.

An iteration of the process 2000 can be performed as often as needed inan ongoing manner. In some embodiments, the process 2000 is performedfor each new SG value (and its corresponding sensor quality metric).

Techniques and technologies may be described herein in terms offunctional and/or logical block components, and with reference tosymbolic representations of operations, processing tasks, and functionsthat may be performed by various computing components or devices. Suchoperations, tasks, and functions are sometimes referred to as beingcomputer-executed, computerized, software-implemented, orcomputer-implemented. It should be appreciated that the various blockcomponents shown in the figures may be realized by any number ofhardware, software, and/or firmware components configured to perform thespecified functions. For example, an embodiment of a system or acomponent may employ various integrated circuit components, e.g., memoryelements, digital signal processing elements, logic elements, look-uptables, or the like, which may carry out a variety of functions underthe control of one or more microprocessors or other control devices.

When implemented in software, firmware, or other form of executableprogram instructions, various elements of the systems described hereinare essentially the code segments or instructions that perform thevarious tasks. In certain embodiments, the program or code segments arestored in a tangible processor-readable medium, which may include anymedium that can store or transfer information. Examples of anon-transitory and processor-readable medium include an electroniccircuit, a semiconductor memory device, a ROM, a flash memory, anerasable ROM (EROM), a floppy diskette, a CD-ROM, an optical disk, ahard disk, or the like.

The various tasks performed in connection with a process describedherein may be performed by software, hardware, firmware, or anycombination thereof. It should be appreciated that a described processmay include any number of additional or alternative tasks, the tasksshown in a flow chart representation need not be performed in theillustrated order, and that a described process may be incorporated intoa more comprehensive procedure or process having additionalfunctionality not described in detail herein. Moreover, one or more ofthe illustrated tasks could be omitted from an embodiment of thedescribed process as long as the intended overall functionality remainsintact.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the described embodiment or embodiments. It should beunderstood that various changes can be made in the function andarrangement of elements without departing from the scope defined by theclaims, which includes known equivalents and foreseeable equivalents atthe time of filing this patent application.

What is claimed is:
 1. A method of controlling operation of a medicaldevice that regulates delivery of a fluid medication to a user, themethod comprising: obtaining a current sensor-generated value that isindicative of a physiological characteristic of the user, the currentsensor-generated value produced in response to operation of a continuousanalyte sensor device; calculating a sensor quality metric thatindicates accuracy of the current sensor-generated value, wherein thesensor quality metric is calculated from information generated by orderived from the continuous analyte sensor device; adjusting, inresponse to the calculated sensor quality metric, therapy actions of themedical device to configure a quality-specific operating mode of themedical device, wherein adjusting the therapy actions comprisesseparately regulating basal and bolus deliveries based on the calculatedsensor quality metric; managing generation of user alerts at the medicaldevice in response to the calculated sensor quality metric; andregulating delivery of the fluid medication from the medical device, inaccordance with the current sensor-generated value and thequality-specific operating mode of the medical device.
 2. The method ofclaim 1, wherein the information comprises sensor age data, raw sensorsignal values, and historical sensor-generated values produced inresponse to operation of the continuous analyte sensor device.
 3. Themethod of claim 1, wherein managing generation of user alerts comprises:generating user alerts when the calculated sensor quality metricsatisfies alert-generating criteria; and inhibiting user alerts when thecalculated sensor quality metric fails the alert-generating criteria. 4.The method of claim 1, wherein: the sensor quality metric is calculatedby the continuous analyte sensor device; the current sensor-generatedvalue is obtained by the medical device; and the method furthercomprises the step of communicating the calculated sensor quality metricfrom the continuous analyte sensor device to the medical device.
 5. Themethod of claim 1, wherein the calculating step calculates the sensorquality metric based on: sensor age data that indicates age of thecontinuous analyte sensor device; measurement noise of raw signal outputof the continuous analyte sensor device; and changes in sensor-generatedvalues that cannot be attributed to a natural physiological condition ofthe user.
 6. The method of claim 1, wherein: the medical device is aninsulin infusion device; the fluid medication comprises insulin; thephysiological characteristic of the user is blood glucose; and thecontinuous analyte sensor device is a continuous glucose sensor device.7. The method of claim 6, wherein: when the sensor quality metricindicates an uncertain quality, the adjusting step enables automaticbasal insulin delivery by the insulin infusion device, disables anautomatic bolus delivery feature of the insulin infusion device, andinhibits generation of any user alert related to the currentsensor-generated value having uncertain quality; when the sensor qualitymetric indicates high quality, the adjusting step enables automaticbasal insulin delivery by the insulin infusion device, enables theautomatic bolus delivery feature, and inhibits generation of any useralert related to the current sensor-generated value having high quality;when the sensor quality metric indicates medium quality, the adjustingstep enables automatic basal insulin delivery by the insulin infusiondevice, enables a restricted automatic bolus delivery feature, andinhibits generation of any user alert related to the currentsensor-generated value having medium quality; and when the sensorquality metric indicates low quality, the adjusting step enables a safebasal insulin delivery mode of the insulin infusion device, disables theautomatic bolus delivery feature, and generates a user alert to promptthe user to take corrective action.
 8. The method of claim 7, whereinthe user alert prompts the user to calibrate the continuous glucosesensor device.
 9. The method of claim 1, wherein the adjusting stepadjusts the therapy actions of the medical device such thataggressiveness of fluid medication therapy is proportional to quality ofthe current sensor-generated value as indicated by the calculated sensorquality metric.
 10. A medical device that regulates delivery ofmedication to a user, the medical device comprising: a drive system; atleast one processor device that regulates operation of the drive systemto deliver a fluid medication from the medical device; a user interface;and at least one memory element associated with the at least oneprocessor device, the at least one memory element storingprocessor-executable instructions configurable to be executed by the atleast one processor device to perform a method of controlling operationof the medical device, the method comprising: obtaining a currentsensor-generated value that is indicative of a physiologicalcharacteristic of the user, the current sensor-generated value producedin response to operation of a continuous analyte sensor device;receiving or calculating a sensor quality metric that indicates accuracyof the current sensor-generated value, wherein the sensor quality metricis calculated from information generated by or derived from thecontinuous analyte sensor device; adjusting therapy actions of themedical device in response to the calculated sensor quality metric, toconfigure a quality-specific operating mode of the medical device,wherein adjusting the therapy actions comprises separately regulatingbasal and bolus deliveries based on the calculated sensor qualitymetric; managing generation of user alerts at the user interface inresponse to the calculated sensor quality metric; and regulatingdelivery of the fluid medication from the medical device, in accordancewith the current sensor-generated value and the quality-specificoperating mode of the medical device.
 11. The medical device of claim10, wherein the medical device receives the sensor quality metric fromthe continuous analyte sensor device.
 12. The medical device of claim10, wherein the medical device calculates the sensor quality metric onlyfrom the information generated by or derived from the continuous analytesensor device.
 13. The medical device of claim 12, wherein the medicaldevice calculates the sensor quality metric based on: sensor age datathat indicates age of the continuous analyte sensor device; measurementnoise of raw signal output of the continuous analyte sensor device; andchanges in sensor-generated values that cannot be attributed to anatural physiological condition of the user.
 14. The medical device ofclaim 10, wherein: the medical device is an insulin infusion device; thefluid medication comprises insulin; the physiological characteristic ofthe user is blood glucose; and the continuous analyte sensor device is acontinuous glucose sensor device.
 15. The medical device of claim 14,wherein: when the sensor quality metric indicates an uncertain quality,the adjusting step enables automatic basal insulin delivery by theinsulin infusion device, disables an automatic bolus delivery feature ofthe insulin infusion device, and inhibits generation of any user alertrelated to the current sensor-generated value having uncertain quality;when the sensor quality metric indicates high quality, the adjustingstep enables automatic basal insulin delivery by the insulin infusiondevice, enables the automatic bolus delivery feature, and inhibitsgeneration of any user alert related to the current sensor-generatedvalue having high quality; when the sensor quality metric indicatesmedium quality, the adjusting step enables automatic basal insulindelivery by the insulin infusion device, enables a restricted automaticbolus delivery feature, and inhibits generation of any user alertrelated to the current sensor-generated value having medium quality; andwhen the sensor quality metric indicates low quality, the adjusting stepenables a safe basal insulin delivery mode of the insulin infusiondevice, disables the automatic bolus delivery feature, and generates auser alert to prompt the user to take corrective action.
 16. The medicaldevice of claim 10, wherein the adjusting step adjusts the therapyactions of the medical device such that aggressiveness of fluidmedication therapy is proportional to quality of the currentsensor-generated value as indicated by the sensor quality metric.
 17. Amethod of assessing operational quality of a continuous analyte sensordevice, the method comprising: obtaining a current sensor-generatedvalue that is indicative of a physiological characteristic of a user,the current sensor-generated value produced in response to operation ofthe continuous analyte sensor device; calculating a sensor qualitymetric that indicates accuracy of the current sensor-generated value,wherein the calculating is based on information generated by or derivedfrom the continuous analyte sensor device; and formatting the sensorquality metric for compatibility with a fluid medication deliverydevice, such that therapy actions of the fluid medication deliverydevice are adjusted in response to the calculated sensor quality metric,and such that aggressiveness of fluid medication therapy provided by thefluid medication delivery device is proportional to quality of thecurrent sensor-generated value as indicated by the calculated sensorquality metric, wherein the therapy actions are adjusted such that basaland bolus deliveries are separately regulated based on the calculatedsensor quality metric.
 18. The method of claim 17, wherein: theinformation comprises sensor age data that indicates age of thecontinuous analyte sensor device, raw sensor output values of thecontinuous analyte sensor device, and historical sensor-generated valuesproduced in response to operation of the continuous analyte sensordevice; and the calculating step calculates the sensor quality metricbased on the sensor age data, measurement noise of the raw sensor outputvalues, and changes in sensor-generated values that cannot be attributedto a natural physiological condition of the user.
 19. The method ofclaim 17, wherein: the fluid medication delivery device is an insulininfusion device; when the sensor quality metric indicates an uncertainquality, the insulin infusion device responds by enabling automaticbasal insulin delivery, disabling an automatic bolus delivery feature,and inhibiting generation of any user alert related to the currentsensor-generated value having uncertain quality; when the sensor qualitymetric indicates high quality, the insulin infusion device responds byenabling automatic basal insulin delivery, enabling the automatic bolusdelivery feature, and inhibiting generation of any user alert related tothe current sensor-generated value having high quality; when the sensorquality metric indicates medium quality, the insulin infusion deviceresponds by enabling automatic basal insulin delivery, enabling arestricted automatic bolus delivery feature, and inhibiting generationof any user alert related to the current sensor-generated value havingmedium quality; and when the sensor quality metric indicates lowquality, the insulin infusion device responds by enabling a safe basalinsulin delivery mode, disabling the automatic bolus delivery feature,and generating a user alert to prompt the user to take correctiveaction.